SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28d620412bf86628772f1e737a241299ecb6df20507f61ce7caad3c263992659' 
  AND token = 'wTF0bIfJ5DMQWCHmMrz4cCDN7bFnJAZdV0RmqAX5gUA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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