You can do one of 2 things:
1. Don’t create a new state. Instead, create an action in a state that will be running during Edit. Select Lock Record for the Action type and under Condition, you will see that Saved Search is a field. If you select your saved search there, whatever records appear in that saved search the action will be performed on
2. Create a transition to a lock state (per your statement). You should set “Transition on” to blank, and use the condition to the right of Saved Search and enter your saved search there. Then in your lock state add a lock record action with no conditions.