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 (
    2702, 2703, 2704, 2705, 2706, 2708, 2709, 
    2710, 2714, 2715, 2716, 2717, 2719, 
    2728, 2723, 2724, 2725, 2726, 2729, 
    2730, 2731, 2732, 2739, 2740, 2741, 
    2742, 2743, 2744, 2745, 2746, 2747, 
    2749, 2750, 2751, 2752, 2753, 2754, 
    2755, 2756, 2757, 2761, 2762, 2763, 
    2764, 2768, 2767, 2760, 3164, 3165, 
    2737, 3255
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00240

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "118.36"
    },
    "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": 132,
            "rows_produced_per_join": 132,
            "filtered": "100.00",
            "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`cscart_products_categories`.`product_id` in (2702,2703,2704,2705,2706,2708,2709,2710,2714,2715,2716,2717,2719,2728,2723,2724,2725,2726,2729,2730,2731,2732,2739,2740,2741,2742,2743,2744,2745,2746,2747,2749,2750,2751,2752,2753,2754,2755,2756,2757,2761,2762,2763,2764,2768,2767,2760,3164,3165,2737,3255))",
            "cost_info": {
              "read_cost": "58.96",
              "eval_cost": "13.20",
              "prefix_cost": "72.16",
              "data_read_per_join": "2K"
            },
            "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": 6,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "33.00",
              "eval_cost": "0.66",
              "prefix_cost": "118.36",
              "data_read_per_join": "20K"
            },
            "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')))"
          }
        }
      ]
    }
  }
}