You can use a cotton swab dipped in alcohol to scrub the keyboard keys. For cracks that are difficult to clean, just find a small stick, like a toothpick, wrap a proper amount of absorbent cloth or soft paper and dip it in alcohol, which makes it easier to wipe off the dust.
Blow off the debris
Blow the gap on the keyboard keys with a hair dryer to blow off the sundries attached to them. Try to raise the temperature of the blower before blowing. High temperature is also beneficial to sterilization.
Vacuum out the keyboard fragments.