Note : Doesn't work on devices with fingerprint sensor.
Donate: Lock It: Screen Off – Donate
No more clicking the power button, one click is all you need to turn off the screen.
Lock It is a very small app while being efficient.
For android versions 4.1(Jelly Bean) to 5.1.1(Lollipop): Swipe up from the home button to lock screen quickly
For Android 6.0(marshmallow) & above: Choose the default Assist app and then long-press the home button to lock the screen.
To uninstall: Go to Settings -> Security -> Device administrators -> deselect Lock It then uninstall in a normal way.