The following item is detected as an Unused File Extension in ccleaner for those using Avira Antivir Premium
Unused File Extension {80b8c23c-16e0-4cd8-bbc3-cecec9a78b79} HKCR\{80b8c23c-16e0-4cd8-bbc3-cecec9a78b79}
When removed it causes no harm whatsoever and Avira simply re-adds the key (if you scan again the same key will be present).
Just wanted to let someone know so that it does not cause later confusion.
I figured this out by searching the key via google as well as uninstalling Avira to see if the issue persisted. It did not once uninstalled.