There have been times when i used 1/4 bottle of deicer to get my lock unfrozen. Either i'm deicer defficient or there was a lot of ice in there.
Regardless, what i found to be of best use, was a blowdryer/hairdryer. It helps if you have a socket nearby your bike. This avoids the whole pouring more liquid into the lock. And yes; keep your locks indoors if possible.