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, 2) 
  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 = 5 
WHERE 
  cscart_products_categories.product_id IN (
    73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 
    84, 85, 91, 90, 86, 87, 88, 92, 89, 99, 
    95, 96, 97, 98, 93, 94
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00155

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.033368335,
    "filesort": {
      "sort_key": "cscart_products_categories.product_id",
      "temporary_table": {
        "nested_loop": [
          {
            "table": {
              "table_name": "cscart_categories",
              "access_type": "ALL",
              "possible_keys": ["PRIMARY", "c_status", "p_category_id"],
              "loops": 1,
              "rows": 7,
              "cost": 0.011130435,
              "filtered": 100,
              "attached_condition": "cscart_categories.storefront_id in (0,2) 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": "cscart_products_categories",
              "access_type": "ref",
              "possible_keys": ["PRIMARY", "pt"],
              "key": "PRIMARY",
              "key_length": "3",
              "used_key_parts": ["category_id"],
              "ref": ["batterycube.cscart_categories.category_id"],
              "loops": 7,
              "rows": 1,
              "cost": 0.012944317,
              "filtered": 54.45544434,
              "index_condition": "cscart_products_categories.product_id in (73,74,75,76,77,78,79,80,81,82,83,84,85,91,90,86,87,88,92,89,99,95,96,97,98,93,94)"
            }
          },
          {
            "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", "batterycube.cscart_products_categories.product_id"],
              "loops": 3.85,
              "rows": 1,
              "cost": 0.00686155,
              "filtered": 100
            }
          }
        ]
      }
    }
  }
}