SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8a8ce15b29819ed40480fddb50a9d2124db1742139685d013f225c617a955e9' 
  AND token = 'mT3IjKnVMQrSP7D+2+iThT9SHqE9saqpSuymqBFj0fs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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