MacBook sticky keys

I would not use WD40 on a keyboard since it will attract and hold dust and dirt. Sticky keys are usually caused by crumbs or liquid residue causing the key cap & scissor/butterfly mechanism to bind. If compressed air doesn't help to make the keys work properly, then the laptop should be repaired by having the keyboard replaced.

https://support.apple.com/en-us/HT205662

If your laptop has the dreaded butterfly keyboards associated with the 2016-2018/9 Macs, then Apple has a free keyboard repair program to address the issue assuming the issue is not caused by liquid damage. However, now that you have sprayed the keys with WD40 you may not be eligible for this free repair program.

Apple free keyboard repair program for some USB-C Apple laptops:

https://support.apple.com/keyboard-service-program-for-mac-notebooks

FYI, here is a current list of the publicly acknowledged free repair programs for various Apple products. Some Apple products have multiple programs available.

https://support.apple.com/exchange_repair

Edit: For older Macs it is possible to remove the key caps and scissor mechanisms to clean them. It is also possible for the butterfly keyboards as well, but the key caps & butterfly mechanism is much more fragile and delicate so I don't recommend anyone doing this on them especially since Apple has the free repair program available. You still must be extremely careful doing this even with older Macs with scissor style keyboard since the plastic snaps & lugs are very fragile and are easily damaged if removed incorrectly.