SELECT 
  product_id 
FROM 
  cscart_mb_ali_products 
WHERE 
  product_id IN (
    20893, 20894, 20895, 20896, 20897, 20898, 
    20899, 20900, 20901, 20902, 20903, 
    20904, 20905, 20906, 20907, 20908
  )

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 (20893,20894,20895,20896,20897,20898,20899,20900,20901,20902,20903,20904,20905,20906,20907,20908)",
      "using_index": true
    }
  }
}