AutoRun Eater monitors all your drives in real-time, so there’s no need for an option to scan a specific drive.
The ‘detection message box’ ONLY appears when a suspicious ‘autorun.inf’ file is present in any of the drives. If nothing appears, your drives is probably void of any ‘autorun.inf’ file(s). Just to be safe, scan the drive with an updated anti-virus app if you doubt it’s safe to access.