SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0c57f018888103042a7fdaa679b1168148cd45ce157341c217cd96a8b89e054' 
  AND token = 'w3CIHC6tmUdkEYvMUdB79qTLLMAYTDQ4WZxkVQbckgk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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