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 (
    3475, 3732, 4113, 4323, 4452, 5322, 5456, 
    5484, 5596, 5842, 6219, 8247, 5064, 
    3025, 3527, 3565, 4551, 4907, 5198, 
    5343, 5381, 5402, 5412, 5564
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00158

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "54.01"
    },
    "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": 60,
            "rows_produced_per_join": 60,
            "filtered": "100.00",
            "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`cscart_products_categories`.`product_id` in (3475,3732,4113,4323,4452,5322,5456,5484,5596,5842,6219,8247,5064,3025,3527,3565,4551,4907,5198,5343,5381,5402,5412,5564))",
            "cost_info": {
              "read_cost": "27.01",
              "eval_cost": "6.00",
              "prefix_cost": "33.01",
              "data_read_per_join": "960"
            },
            "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": 3,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "15.00",
              "eval_cost": "0.30",
              "prefix_cost": "54.01",
              "data_read_per_join": "9K"
            },
            "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')))"
          }
        }
      ]
    }
  }
}

Result

product_id category_ids
3025 166,329
3475 167,166,354M
3527 452,424,423,166M
3565 167,166,354M
3732 423,166,449M
4113 219,503M
4323 219,494,496,507M
4452 219,504M
4551 167,166,519M
4907 513,166,517M
5064 513,166,516M
5198 166,250,328,402,404,341M
5322 372,552,550M
5343 372,552,550M
5381 538,521,540M
5402 372,466,467M
5412 473,577,474M
5456 521,522,535M
5484 466,372,575M
5564 554,553,250,552,372,556M
5596 522,521,535M
5842 372,583M
6219 574M
8247 631M