You’re right; in the layers palette are two padlocks. The black one locks the layer so you can’t change anything on it. The other padlock is to lock the transparent pixels in that layer.
I end up with LOTS o’ layers, so I usually group them in folders. (The ‘new folder’ is at the bottom of the layers palette.) You can put whatever layers you want into the folder, name it, and then lock the folder, which locks everything in it.
Does that help what you’re looking to do?
I had lots of teeth gnashing initially when I switched to CC, but there’s a lot I like about it.