Rendering an animation with one render layer never changing

Basically, I have 2 render layers in a single scene

What I would like to do, is render an animation with only a single one of those render layers. Essentially, the first render layer is always going to remain the same. The problem is when I render, it renders both layers, one right after the other. Since the first layer never changes (it’s only used as a shadow map give depth to the second render layer), it’s an unnecessary waste of time to render that layer.

Is this possible?

Disable the other, F12 render, save as multilayer .exr, and use that image in the compositor instead of render layer.