SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    65814, 65815, 65720, 65732, 65805, 65804, 
    65733, 65813, 65734, 65101, 65721, 
    65685
  )

Query time 0.00077

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 (65814,65815,65720,65732,65805,65804,65733,65813,65734,65101,65721,65685)"
    }
  }
}

Result