The import of new keys can be found on the “Keys” page. However, only the assigned keys are listed there. After an import, you won't see the newly imported keys there. Actually, “you don't need the import function there.

You would actually need the import function when assigning keys to a user, because it is only there that you can determine whether a key is known in the system. You then have to cancel the assignment dialog, go to the keys page, import there, then call up the assignment dialog again.