SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5939908df5d9987b568833ab090ea6ded96b920374453d401b38734b9268efa0' 
  AND token = '/MjGUocye2GKxH0iylVj6AkRaufBDOhhxFyA6iOyRWg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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