SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3d54c6eb1ec9f90b970c767086a6ed8497412ec05f80a9171018feb81dbae2c' 
  AND token = 'YIhJZPcluQrEmIZxJZbbyK0IL+i6FjPg0SsPmlwm6Z8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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