SELECT 
  product_id 
FROM 
  cscart_mb_ali_products 
WHERE 
  product_id IN (
    21919, 21920, 21921, 21922, 21923, 21924, 
    21925, 21926, 21927, 21928, 21929, 
    21930, 21931, 21932, 21933, 21934
  )

Query time 0.00015

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_mb_ali_products",
      "access_type": "range",
      "possible_keys": ["product_id"],
      "key": "product_id",
      "key_length": "4",
      "used_key_parts": ["product_id"],
      "rows": 16,
      "filtered": 100,
      "attached_condition": "cscart_mb_ali_products.product_id in (21919,21920,21921,21922,21923,21924,21925,21926,21927,21928,21929,21930,21931,21932,21933,21934)",
      "using_index": true
    }
  }
}