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 (
    8633, 8619, 8458, 8576, 8611, 8470, 8468, 
    8591, 8526, 8622, 8596, 8469, 8597, 
    8583, 8657, 8462, 8601, 8465, 8621, 
    8651, 8544, 8646, 8660, 8625, 8618, 
    8064, 8594, 8607, 8087, 8065, 8073, 
    8061, 8647, 8634, 8435, 8683, 8070, 
    8056, 8724, 8709, 8067, 10982, 8080, 
    8711, 8712, 8723, 8554, 8649, 8731, 
    8537, 8538, 8532, 8522, 8631, 8605, 
    8445, 8713, 8533, 8612, 8681, 8672, 
    8705, 8539, 8455, 8674, 8635, 8075, 
    8675, 10201, 8632, 8626, 63370, 13303, 
    8063, 64621, 64630, 64650, 64633
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00219

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "137.91"
    },
    "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": 148,
            "rows_produced_per_join": 148,
            "filtered": "100.00",
            "index_condition": "(`cscartdb`.`cscart_products_categories`.`product_id` in (8633,8619,8458,8576,8611,8470,8468,8591,8526,8622,8596,8469,8597,8583,8657,8462,8601,8465,8621,8651,8544,8646,8660,8625,8618,8064,8594,8607,8087,8065,8073,8061,8647,8634,8435,8683,8070,8056,8724,8709,8067,10982,8080,8711,8712,8723,8554,8649,8731,8537,8538,8532,8522,8631,8605,8445,8713,8533,8612,8681,8672,8705,8539,8455,8674,8635,8075,8675,10201,8632,8626,63370,13303,8063,64621,64630,64650,64633))",
            "cost_info": {
              "read_cost": "71.31",
              "eval_cost": "14.80",
              "prefix_cost": "86.11",
              "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": [
              "cscartdb.cscart_products_categories.category_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 7,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "37.00",
              "eval_cost": "0.74",
              "prefix_cost": "137.91",
              "data_read_per_join": "24K"
            },
            "used_columns": [
              "category_id",
              "storefront_id",
              "usergroup_ids",
              "status"
            ],
            "attached_condition": "((`cscartdb`.`cscart_categories`.`storefront_id` in (0,1)) and ((`cscartdb`.`cscart_categories`.`usergroup_ids` = '') or (0 <> find_in_set(0,`cscartdb`.`cscart_categories`.`usergroup_ids`)) or (0 <> find_in_set(1,`cscartdb`.`cscart_categories`.`usergroup_ids`))) and (`cscartdb`.`cscart_categories`.`status` in ('A','H')))"
          }
        }
      ]
    }
  }
}