Ordinary lock is temporary, usually when there is a dispute in comments, or edit war. It does not mean the question is off topic, or that the post should be deleted. Even very good questions/answers can be locked that way. So having the voting buttons in place mean, in my opinion, that you can vote, in theory, just not now in the current state of the post. It is also consistent with deleted posts, where you can also see the voting buttons and click them.
Historical lock, on the other hand, is a totally different thing. It's is a powerful version of the ordinary lock, and is put on questions which are off topic for the site and would otherwise be deleted. Hence, it's is a permanent lock which will never be removed, so hiding the vote arrows there is clear sign for this.