There is a registry tweak that I have JUST modified and so far it has worked. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\7516b95f-f776-4464-8c53-06167f40cc99\8ec4b3a5-6868-48c2-be75-4f3044be88a7, then find (usually the last value) ValueUnits, it's string will say @%SystemRoot%\system32\powrprof.dll,-80,Seconds, Change this -80 to however much time (in seconds, obviously) you want the screen to remain on before you would usually log in, even the whole day in seconds if that is what you want. I have not found this anywhere else and I have been trying to figure it out for ages. The last solution I 'tried' I didn't realise was a windows 10 solution as the value it stated wasn't there, so investigated the strings of everything that was there until I came to the one I have stated which revealed (as you can see) a time component. Change that to your preference and you should have a lock screen that behaves the way you want it.
