From reading I have done they are still good but you will/may/should experience about 25% less germination. Some say to combat it just up your seeding ratio. For food plots I think you will be fine.
I guess I could have given more of an answer. We used to plant year-old oats, and we always planted an extra bushel per acre (4 instead of 3). Never had a problem getting a good stand. Buck Forage Oats probably comes in a pretty decent bag, too-that will help protect the seed. We were planting bulk out of a bin.