SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df694b81beecfad4227fed60a4ed4ddb69059b9fcda4e7bd1fe1041020dfee61' 
  AND token = 'dQRmNdOQh16S8Zi6TcpWj82rSkSWI8uDuWWQO7fvORQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}