...can I spray them with WD-40?

Probably, I spray everything with wd-40. Even computer fans, when they get noisy, I'll spray wd-40 into the middle part.

As long as it isnt conductive, then it shouldnt matter. Make sure it isnt first, otherwise you risk frying your screen and most likely the entire laptop as well.

I don't recommend using WD-40 on plastic parts. Silicone oil is better suited for that.