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 (
    908, 134, 1254, 1253, 247, 2109, 2108, 
    2107, 2265, 2264, 2263, 2253, 2363, 
    2364, 2365, 2395, 2396, 2397, 2398, 
    2467, 2468, 2469, 2470, 2471, 2472, 
    2473, 2475, 2476, 2477, 2478, 2483, 
    2482, 2484, 2485, 2486, 2487, 2488, 
    2489, 2490, 2491, 2492, 2493, 2494, 
    2495, 2496, 2497, 2503, 2504, 2505, 
    2508, 2512, 2509, 2524, 2525, 2526, 
    2527, 2528, 2529, 2530, 2531, 2538, 
    2540, 2541, 2550, 2549, 2548, 2544, 
    2551, 2552, 2534, 2564, 2565, 2571, 
    2572, 8422, 2574, 2576, 2577, 2578, 
    2579, 2580, 2596, 2597, 2598, 2599, 
    2600, 2601, 2602, 2604, 2605, 2606, 
    2607, 2608, 2615, 2620, 2621, 2637, 
    2638, 2502, 3639, 2432, 8485, 8484, 
    8483, 2459, 8492, 8491, 8493
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00514

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "265.41"
    },
    "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": 298,
            "rows_produced_per_join": 298,
            "filtered": "100.00",
            "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`cscart_products_categories`.`product_id` in (908,134,1254,1253,247,2109,2108,2107,2265,2264,2263,2253,2363,2364,2365,2395,2396,2397,2398,2467,2468,2469,2470,2471,2472,2473,2475,2476,2477,2478,2483,2482,2484,2485,2486,2487,2488,2489,2490,2491,2492,2493,2494,2495,2496,2497,2503,2504,2505,2508,2512,2509,2524,2525,2526,2527,2528,2529,2530,2531,2538,2540,2541,2550,2549,2548,2544,2551,2552,2534,2564,2565,2571,2572,8422,2574,2576,2577,2578,2579,2580,2596,2597,2598,2599,2600,2601,2602,2604,2605,2606,2607,2608,2615,2620,2621,2637,2638,2502,3639,2432,8485,8484,8483,2459,8492,8491,8493))",
            "cost_info": {
              "read_cost": "131.31",
              "eval_cost": "29.80",
              "prefix_cost": "161.11",
              "data_read_per_join": "4K"
            },
            "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": 14,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "74.50",
              "eval_cost": "1.49",
              "prefix_cost": "265.41",
              "data_read_per_join": "46K"
            },
            "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')))"
          }
        }
      ]
    }
  }
}