SELECT 
  product_id 
FROM 
  cscart_mb_ali_products 
WHERE 
  product_id IN (
    21743, 21744, 21745, 21746, 21747, 21748, 
    21749, 21750, 21751, 21752, 21753, 
    21754, 21755, 21756, 21757, 21758
  )

Query time 0.00023

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 (21743,21744,21745,21746,21747,21748,21749,21750,21751,21752,21753,21754,21755,21756,21757,21758)",
      "using_index": true
    }
  }
}