Scratching around the head with the hind feet can just be normal scratching. Rabbits will scratch at their ears to get the ear wax out. It's when the scratching seems unusually excessive that it means there could be something going on there. And the crustiness at the corner of the eye, if it's just a tiny bit that isn't thick sticky and white, but is just a tiny bit that comes away, it sounds like it could just be normal eye crusties. But if the scratching does seem excessive, and/or if the eye crustiness is thick goopy discharge crusting up the fur around the eye, then best to have a knowledgeable rabbit vet check your rabbit out.
https://rabbit.org/vet-listings/