PIR sensor right next to the reader? That way you maintain the whole hand wavy magic bit. You could even remove the white dome lense, since you don’t need a very wide angle. They consume less than 2mA, so it’s not as power efficient as a momentary switch, but it would bump you from 254hrs to 2000hrs between charge.
If you want a capacitive touch module, you could use a momentary one like this from Adafruit. It can be modified to run at 50uA. Hypothetically you could use the entire toolbox as the touch sensor, you would just need to get to the metal under the paint.