There are only two options for the Key Redirect module, which are conigurable from the administration page.

1. Key Expiration Time: The number of minutes after which a key will be deleted. Keep in mind that the deletion process is run by hook_cron. This value mostly prevents keys from being inadvertently deleted before they can be used.
2. Key Length: The length of the key you wish to generate, which will be returned in the response as a URL, i.e. http://yoursite.com/krd/Kf7BkdEGUckueiHwQzDHm95YDv9swU. Longer keys are less susceptible to exploitation. The default is 30.