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 = 18 
WHERE 
  cscart_products_categories.product_id IN (
    189, 192, 168, 188, 183, 813, 814, 749, 
    203, 196, 165, 167, 701, 702, 708, 786, 
    221, 166, 184, 751, 856, 193, 789, 791, 
    793, 224, 160, 228, 727, 728, 729, 730, 
    731, 800, 806, 169, 200
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00060

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.19797006,
    "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": 63,
          "cost": 0.041440115,
          "filtered": 100,
          "attached_condition": "cscart_products_categories.product_id in (189,192,168,188,183,813,814,749,203,196,165,167,701,702,708,786,221,166,184,751,856,193,789,791,793,224,160,228,727,728,729,730,731,800,806,169,200)",
          "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": [
            "u428615623_ecartifygonje.cscart_products_categories.category_id"
          ],
          "loops": 63,
          "rows": 1,
          "cost": 0.05716892,
          "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",
            "u428615623_ecartifygonje.cscart_products_categories.product_id"
          ],
          "loops": 63,
          "rows": 1,
          "cost": 0.05880732,
          "filtered": 100
        }
      }
    ]
  }
}