SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '69baf3358697051fab29ce879f52471de4ae705b2639283b62c1897392ea6ad3' 
  AND token = 'mCQjbGzYN5KXZOWAhQkScZoD7XXi+1ujAEmNIPKOkB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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