This is a simple two-line script that locks the screen, then puts the system to sleep (it uses qdbus and KDE's power management system for these actions, hence its listing on KDE Apps). KDE gives the option to always lock the screen before going to sleep, but half the time I suspend my system, locking it isn't necessary. I recommend setting a keyboard shortcut in KDE Menu Editor for easy access.
Extract the archive, copy the .sh file to your path, the .desktop file to ~/.local/share/applications/, and the .png file to ~/.local/share/icons/. You can find it under Utilities in the applications menu.