SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d15e3829cd42225338c33e1797aa18ae38fbdfb963670e558074a31cf3e155e' 
  AND token = '/on5xfmTwb6hJlK7q6ma8FZ7wI+SzjgxosmPRHOY300=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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