How would I quickly defrost chicken if it's going to be cooked in a crock pot?
Either microwave or the running water method should be perfectly acceptable, since you are going to begin cooking right away.  Modern slow cookers should come up to temperature within no more than an hour or so, so you aren't leaving the food at ambient temperature for very long.

Note that for the water method, the water should be running--it doesn't have to be fast, just a thin stream--but this makes sure there is enough circulation in the water to substantially reduce the defrosting time.

Your best, safest bet, if you have the time is always to defrost in the refrigerator.   The other methods are for when you don't have time to do that.