A workshop can be a natural attraction for young children. Make sure that whenever children are in a space where there are power tools, an adult is with them. As added protection, store your tools well out of their reach.
While not a substitute for supervision, threading a key ring through the hole in the plug makes it impossible to plug in power tools and can be a valuable last line of defense.
Taking steps to protect children from potentially dangerous tools is always worth a few extra seconds.