Unfortunately, such functionality hasn't been exposed out of the box yet.
In order to achieve this within an AppBuilder application you will need to first develop a custom cordova plugin
(you can also check this
link from our documentation) that natively overrides all the required Android functions. Then, importing it to your project
should do the trick about locking the device after the application has started.
Please, note that custom Cordova plugins are being intensively developed lately. And probably it is just a matter of time for such to be made.
I hope this answers your question.