SELECT 
  tmall_products_categories.product_id, 
  GROUP_CONCAT(
    IF(
      tmall_products_categories.link_type = "M", 
      CONCAT(
        tmall_products_categories.category_id, 
        "M"
      ), 
      tmall_products_categories.category_id
    )
  ) AS category_ids 
FROM 
  tmall_products_categories 
  INNER JOIN tmall_categories ON tmall_categories.category_id = tmall_products_categories.category_id 
  AND tmall_categories.storefront_id IN (0, 1) 
  AND (
    tmall_categories.usergroup_ids = '' 
    OR FIND_IN_SET(
      0, tmall_categories.usergroup_ids
    ) 
    OR FIND_IN_SET(
      1, tmall_categories.usergroup_ids
    )
  ) 
  AND tmall_categories.status IN ('A', 'H') 
WHERE 
  tmall_products_categories.product_id IN (
    94, 96, 114, 108, 121, 103, 95, 112, 89, 
    116, 82, 85, 88, 110, 93, 87, 118, 83, 
    123, 119
  ) 
GROUP BY 
  tmall_products_categories.product_id

Query time 0.00780

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.08853058,
    "nested_loop": [
      {
        "table": {
          "table_name": "tmall_products_categories",
          "access_type": "range",
          "possible_keys": ["PRIMARY", "pt"],
          "key": "pt",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "loops": 1,
          "rows": 21,
          "cost": 0.038585831,
          "filtered": 100,
          "index_condition": "tmall_products_categories.product_id in (94,96,114,108,121,103,95,112,89,116,82,85,88,110,93,87,118,83,123,119)"
        }
      },
      {
        "table": {
          "table_name": "tmall_categories",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY", "c_status", "p_category_id"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["category_id"],
          "ref": ["tmall.tmall_products_categories.category_id"],
          "loops": 21,
          "rows": 1,
          "cost": 0.036514346,
          "filtered": 100,
          "attached_condition": "tmall_categories.storefront_id in (0,1) and (tmall_categories.usergroup_ids = '' or find_in_set(0,tmall_categories.usergroup_ids) or find_in_set(1,tmall_categories.usergroup_ids)) and tmall_categories.`status` in ('A','H')"
        }
      }
    ]
  }
}