FWIW, on my 10.13.2 install I checked ALL the prefPanes to ensure that it was only the App Store prefPane with this issue.....and on my other Macs with earlier OS's the App Store prefPane has no padlock to deal with.
Gaining access to the App Store with no unlock required through the prefPane seems a non-issue in my view as the App Store is directly accessible through the Finder.....if someone has physical access to my machine.
