Keyboard shortcut to paste in Windows command prompt

Press Alt+Space followed by E and finally P

This will open the alt Menu > Edit > Paste

Checkout this Stackoverflow article. They provide an AutoHotKey script. If you aren't familiar with AutoHotKey you should be. It is a free application that allows you to automate a ton of things on Windows. I use it for a number of tasks. You can even compile the scripts and then just run the executable. Great for distribution to less tech savvy folks or for running off a thumb drive for portability.

They also mention this:

ALT+SPACE+E+K <-- for copy

ALT+SPACE+E+P <-- for paste

Finally in Windows 10:

Unfortunately Microsoft resists to add SHIFT+INSERT ((