You should see the keyboard I inherited from a co-worker who moved desks. It was far worse than that one. It also had the left over bread crumbs in it from about 6 months ago.
I do what I always do with these things. Unplug them from the computer and get the antic spray on a piece of damp cloth or kitchen towel and start scrubbing the mess away. Sometimes, if I'm feeling like it needs a good scrub, I remove some of the keys from their places with the help of a paperclip and blow under the board.