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 (
    8607, 8700, 8725, 8798, 8807, 8271, 8274, 
    8278, 8279, 8285, 8287, 8330, 8333, 
    8374, 8389, 8405, 8430, 8458, 8465, 
    8516, 8518, 8537, 8571, 8582, 8584, 
    8588, 8599, 8726, 8728, 8755, 8756, 
    8803, 8809, 8268, 8331, 8334, 8378, 
    8383, 8436, 8442, 8462, 8539, 8541, 
    8579, 8583, 8606, 8727, 8239, 8270, 
    8286, 8376, 8384, 8401, 8402, 8437, 
    8467, 8468, 8515, 8531, 8533, 8542, 
    8616, 8698, 8707, 8386, 8404, 8449, 
    8522, 8591, 8592, 8598, 8786, 8808
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00263

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "83.06"
    },
    "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": 81,
            "rows_produced_per_join": 81,
            "filtered": "100.00",
            "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`cscart_products_categories`.`product_id` in (8607,8700,8725,8798,8807,8271,8274,8278,8279,8285,8287,8330,8333,8374,8389,8405,8430,8458,8465,8516,8518,8537,8571,8582,8584,8588,8599,8726,8728,8755,8756,8803,8809,8268,8331,8334,8378,8383,8436,8442,8462,8539,8541,8579,8583,8606,8727,8239,8270,8286,8376,8384,8401,8402,8437,8467,8468,8515,8531,8533,8542,8616,8698,8707,8386,8404,8449,8522,8591,8592,8598,8786,8808))",
            "cost_info": {
              "read_cost": "46.61",
              "eval_cost": "8.10",
              "prefix_cost": "54.71",
              "data_read_per_join": "1K"
            },
            "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": 4,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "20.25",
              "eval_cost": "0.41",
              "prefix_cost": "83.06",
              "data_read_per_join": "12K"
            },
            "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')))"
          }
        }
      ]
    }
  }
}