First of all, don’t eat or drink by your computer. Drinking is even worse because if something spills, it could ruin the inside mechanisms. If you had a plastic keyboard cover, you could easily shake off crumbs and wash the stickiness off. I am assuming that you don’t, so you can clean off visible chametz with a Q-tip between the keys and then spray a compressed air can to extract anything leftover.
P.S. Your computer probably came with little cleaning brushes that are more effective than Q-tips.