SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd79d749543f94e21727ae3ec436811456d2c9cdaddc264831302d657c446e124' 
  AND token = 'Sbj4jczWR6MOUQMd1XFKrXkTgBHArJaZ+lhyzZgRs8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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