SELECT 
  product_id 
FROM 
  cscart_mb_ali_products 
WHERE 
  product_id IN (
    20125, 20126, 20127, 20128, 20129, 20130, 
    20131, 20132, 20133, 20134, 20135, 
    20136, 20137, 20138, 20139, 20140
  )

Query time 0.00012

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 (20125,20126,20127,20128,20129,20130,20131,20132,20133,20134,20135,20136,20137,20138,20139,20140)",
      "using_index": true
    }
  }
}