May 21 @ 6:00 am – 6:00 pm
Polls are open from 6:00 AM to 6:00 PM local time. If you are in line at 6:00 PM, you will be allowed to vote.
Kentucky is a closed primary state, meaning that for primary elections registered Republicans can only see and vote for Republican candidates and vice versa for Democrats. A sample ballot for the Primary Election can be found here.