Sandbox

SELECT 
  rate_id, 
  shipping_id, 
  rate_value, 
  destination_id, 
  base_rate 
FROM 
  cscart_shipping_rates 
WHERE 
  shipping_id = 7 
  AND destination_id = 12 
ORDER BY 
  destination_id desc

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}