If a question is close worthy, but hasn't been touched in years should I vote to close?
It seems wrong to necro-moderate, but presumably it helps clean up the site.
There's no reason not to VTC if you think it is VTC worthy, BUT:
If there's no activity on the post, there's less chances 4 other people would notice it and join VTC (depending on how active Close queue reviewers are, I guess); so your chances of success are low(er)
If it still isn't closed, there's a chance you're not necessarily correct in assuming it should be VTCed. That's just a heuristic - it's possible it simply slipped through the cracks. IOW, think twice if it deserves a VTC, but don't let that consideration stop you if you're sure.
If you have a finite amount of effort you can put in, you'll definitely do more good moderating more recent content (the goal of closing a question is largely to prevent poor answers from being posted. If the question is old, it either already had them posted, or none were - and chances of new ones are low). But if you're already looking at old VTCable Q, go for it.
Our rule of thumb on SO is we don't go out of our way to touch older questions unless they're promoting new problems (i.e. an old opinion question gets a new answer).
What plays in your favor here is that the queues are non-existent (SO perpetually has 8-10k in the Close Vote Queue) so your CV won't get lost in the shuffle. But I think queue participation is also low. Just remember that close votes age away after 14 days