Switching Image Textures During Animation, Game Model (Blender to Unity)

Hi, I’m working on a simple character for a mobile game, building the character and animations in Blender to be used in Unity. I want to have the eyes blink during an animation. I painted the eyes in Blender on an image texture using the UV/Image editor paint mode. I made one image with the eyes open and one closed. I found a tutorial that shows how to switch the image texture during animation using a MixRGB node, 2 image texture nodes and keyframes. Basically you just slide the factor between keyframes. Here’s the tutorial:

The first problem is that it only reflects the change in rendered mode, not material or texture mode. The 2nd thing is - I can’t figure out how to get it to work in Unity. Can anyone either help me figure that out, or show me another way to switch image textures during an animation for a game character? Thanks in advance!