There are examples of canned food going back to WW1 that are still good. And honeyed goods from centuries ago that are still fine!
I'd accept 100 years, 300 years is maybe a bit too far. Still there might be a can here and there that maybe could survive.
Honey can survive indefinitely but can you live on honey?
Can fruit trees survived 300 years untended or maybe little trees just self-seeded?