SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    65656, 65658, 65812, 65821, 65802, 65810, 
    65819, 65809, 65822, 65820, 65811, 
    65806
  )

Query time 0.00081

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_products",
      "access_type": "range",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 12,
      "filtered": 100,
      "attached_condition": "cscart_products.product_id in (65656,65658,65812,65821,65802,65810,65819,65809,65822,65820,65811,65806)"
    }
  }
}

Result