My keyboard works fine but some of the keys hesitate to press. This makes typing really difficult.
I have not figured out how to take it apart since there are no screws at all on the front or back.
Quick and easy: try to pop off offending key caps and carefully clean through the hole with a damp cotton swab. Though I'm not familiar with the Microsoft Sculpt Ergonomic Keyboard, most key caps (other than Space, Enter and Shift) can be removed by pulling on a hook made from a paper clip or with strong sewing thread pushed underneath.
If many keys are badly stuck and if the drink is completely water-soluble (e.g. soda) as opposed to a mixture (such as hot chocolate), the keyboard can be washed in high purity or distilled water (not tap water, rainwater or deionized water), even immersed in it. Of course, the keyboard will not be usable for a while.
If the keyboard has a battery, as all wireless keyboards do, the battery must be removed first and not reinserted until the unit is completely dry, inside and out. It should not be plugged into a port until dry, either.
To speed up drying, the keyboard can be rinsed in 99% ethanol or isopropanol, but that adds to the cost of repair.