SELECT 
  cscart_products_categories.product_id, 
  GROUP_CONCAT(
    IF(
      cscart_products_categories.link_type = "M", 
      CONCAT(
        cscart_products_categories.category_id, 
        "M"
      ), 
      cscart_products_categories.category_id
    )
  ) AS category_ids 
FROM 
  cscart_products_categories 
  INNER JOIN cscart_categories ON cscart_categories.category_id = cscart_products_categories.category_id 
  AND cscart_categories.storefront_id IN (0, 1) 
  AND (
    cscart_categories.usergroup_ids = '' 
    OR FIND_IN_SET(
      0, cscart_categories.usergroup_ids
    ) 
    OR FIND_IN_SET(
      1, cscart_categories.usergroup_ids
    )
  ) 
  AND cscart_categories.status IN ('A', 'H') 
WHERE 
  cscart_products_categories.product_id IN (
    919, 
    918, 
    924, 
    922, 
    921, 
    925, 
    525, 
    917, 
    916, 
    955, 
    942, 
    941, 
    446, 
    953, 
    952, 
    951, 
    949, 
    948, 
    947, 
    946, 
    945, 
    944, 
    982, 
    980, 
    979, 
    978, 
    981, 
    478, 
    977, 
    975, 
    974, 
    973, 
    972, 
    971, 
    970, 
    994, 
    996, 
    493, 
    985, 
    986, 
    988, 
    990, 
    991, 
    993, 
    1003, 
    1001, 
    1000, 
    508, 
    1322, 
    1262, 
    1317, 
    1318, 
    1319, 
    1320, 
    1321, 
    1256, 
    1395, 
    1396, 
    1397, 
    1399, 
    1406, 
    1407, 
    1408, 
    1409, 
    1410, 
    1411, 
    1412, 
    1273, 
    1425, 
    1427, 
    1428, 
    1429, 
    1431, 
    1266, 
    1442, 
    1447, 
    1263, 
    1458, 
    2467, 
    2468, 
    2469, 
    2470, 
    2471, 
    2472, 
    2478, 
    2483, 
    2482, 
    2484, 
    2485, 
    2486, 
    2487, 
    2488, 
    2489, 
    2490, 
    2491, 
    2492, 
    2493, 
    2494, 
    2495, 
    2496, 
    2497, 
    2524, 
    2525, 
    2526, 
    2527, 
    2528, 
    2529, 
    2530, 
    2531, 
    2576, 
    2577, 
    2578, 
    2615, 
    2620, 
    2621, 
    4526, 
    4527, 
    4528, 
    4529, 
    4530, 
    4532, 
    4533, 
    5727, 
    5729, 
    5730, 
    5731, 
    5732, 
    5733, 
    5734, 
    5735, 
    5736, 
    5739, 
    5741, 
    5742, 
    5743, 
    5744, 
    5745, 
    5746, 
    5747, 
    5748, 
    5749, 
    5750, 
    5752, 
    5753, 
    5754, 
    5755, 
    5756, 
    5757, 
    5758, 
    5759, 
    5760, 
    5761, 
    5762, 
    7004, 
    7005, 
    7006, 
    7007, 
    7008, 
    7009, 
    7010, 
    7011, 
    7012, 
    7013, 
    7014, 
    7015, 
    10284, 
    10285, 
    10286, 
    10287, 
    10288, 
    10289, 
    10290, 
    10291, 
    10292, 
    10293
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00695

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "343.76"
    },
    "grouping_operation": {
      "using_filesort": false,
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_products_categories",
            "access_type": "range",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "pt",
            "used_key_parts": [
              "product_id"
            ],
            "key_length": "3",
            "rows_examined_per_scan": 375,
            "rows_produced_per_join": 375,
            "filtered": "100.00",
            "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`cscart_products_categories`.`product_id` in (919,918,924,922,921,925,525,917,916,955,942,941,446,953,952,951,949,948,947,946,945,944,982,980,979,978,981,478,977,975,974,973,972,971,970,994,996,493,985,986,988,990,991,993,1003,1001,1000,508,1322,1262,1317,1318,1319,1320,1321,1256,1395,1396,1397,1399,1406,1407,1408,1409,1410,1411,1412,1273,1425,1427,1428,1429,1431,1266,1442,1447,1263,1458,2467,2468,2469,2470,2471,2472,2478,2483,2482,2484,2485,2486,2487,2488,2489,2490,2491,2492,2493,2494,2495,2496,2497,2524,2525,2526,2527,2528,2529,2530,2531,2576,2577,2578,2615,2620,2621,4526,4527,4528,4529,4530,4532,4533,5727,5729,5730,5731,5732,5733,5734,5735,5736,5739,5741,5742,5743,5744,5745,5746,5747,5748,5749,5750,5752,5753,5754,5755,5756,5757,5758,5759,5760,5761,5762,7004,7005,7006,7007,7008,7009,7010,7011,7012,7013,7014,7015,10284,10285,10286,10287,10288,10289,10290,10291,10292,10293))",
            "cost_info": {
              "read_cost": "175.01",
              "eval_cost": "37.50",
              "prefix_cost": "212.51",
              "data_read_per_join": "5K"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        },
        {
          "table": {
            "table_name": "cscart_categories",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id"
            ],
            "key_length": "3",
            "ref": [
              "softwarepirmam_hewadelivard_cscart_4.cscart_products_categories.category_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 18,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "93.75",
              "eval_cost": "1.88",
              "prefix_cost": "343.76",
              "data_read_per_join": "58K"
            },
            "used_columns": [
              "category_id",
              "storefront_id",
              "usergroup_ids",
              "status"
            ],
            "attached_condition": "((`softwarepirmam_hewadelivard_cscart_4`.`cscart_categories`.`storefront_id` in (0,1)) and ((`softwarepirmam_hewadelivard_cscart_4`.`cscart_categories`.`usergroup_ids` = '') or (0 <> find_in_set(0,`softwarepirmam_hewadelivard_cscart_4`.`cscart_categories`.`usergroup_ids`)) or (0 <> find_in_set(1,`softwarepirmam_hewadelivard_cscart_4`.`cscart_categories`.`usergroup_ids`))) and (`softwarepirmam_hewadelivard_cscart_4`.`cscart_categories`.`status` in ('A','H')))"
          }
        }
      ]
    }
  }
}