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, 
  product_position_source.position AS position 
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') 
  LEFT JOIN cscart_products_categories AS product_position_source ON cscart_products_categories.product_id = product_position_source.product_id 
  AND product_position_source.category_id = 287 
WHERE 
  cscart_products_categories.product_id IN (
    451077, 403015, 438963, 450825, 401687, 
    443424, 427907, 457801, 454192, 427353, 
    414432, 436128, 421748, 421122, 417392, 
    431455, 406944, 412740, 424119, 412948, 
    446814, 438098, 417337, 414479, 403309, 
    408867, 432076, 429951, 443506, 447548, 
    411429, 410643, 457524, 312409, 312424, 
    312425, 414573, 443819, 451444, 413123, 
    402148, 438958, 422426, 446892, 423821, 
    449843, 410922, 450729
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00110

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.243691242,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_products_categories",
          "access_type": "range",
          "possible_keys": ["PRIMARY", "pt"],
          "key": "pt",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "loops": 1,
          "rows": 48,
          "cost": 0.08683616,
          "filtered": 100,
          "attached_condition": "cscart_products_categories.product_id in (451077,403015,438963,450825,401687,443424,427907,457801,454192,427353,414432,436128,421748,421122,417392,431455,406944,412740,424119,412948,446814,438098,417337,414479,403309,408867,432076,429951,443506,447548,411429,410643,457524,312409,312424,312425,414573,443819,451444,413123,402148,438958,422426,446892,423821,449843,410922,450729)",
          "using_index": true
        }
      },
      {
        "table": {
          "table_name": "cscart_categories",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY", "c_status", "p_category_id"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["category_id"],
          "ref": ["u985510652_ecartify.cscart_products_categories.category_id"],
          "loops": 48,
          "rows": 1,
          "cost": 0.04375232,
          "filtered": 100,
          "attached_condition": "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')"
        }
      },
      {
        "table": {
          "table_name": "product_position_source",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY", "pt"],
          "key": "PRIMARY",
          "key_length": "6",
          "used_key_parts": ["category_id", "product_id"],
          "ref": [
            "const",
            "u985510652_ecartify.cscart_products_categories.product_id"
          ],
          "loops": 48,
          "rows": 1,
          "cost": 0.08225472,
          "filtered": 100
        }
      }
    ]
  }
}