The Hardy Tree

Almost any grain or bean, dried and put in a mylar bag, inside a food grade bucket with oxygen absorbers should last at least 20-30 years. Honey is the only thing that requires no special packaging to last a really long time.

Grits! Ignore the date on that package, those instant dry grits will probably last forever.

Well, you are going to need protein so I'd go with a whey protein powder which keeps for a while as long as it isn't opened (so small containers).
Water doesn't go bad as long as it is clean, and something you will need a lot of.
There is salt, which doesn't go bad and can be used to preserve stuff that you've killed to eat post apocalypse.
Grains, beans, and pastas last about 8 years as long as they are stored properly and are away from bugs.
Also, don't forget about a first aid kit. None of that stuff is useful if you nick yourself and get gangrene and die.
Also, I would like to say that I am not prepared for the apocalypse, I just researched for like 10 minutes.

Tactical bacon, of course!

Rice does pretty good. Keeps long, cheap, high in calories.
I'm told canned meats last a long time, but they're heavy, and salty.
Potassium iodide can sanitize water if you're willing to suffer the awful taste. And hey! Bonus nuclear fallout radiation protection for you thyroid. Vitamin C can help with the taste, double bonus!
I'd put multivitamins in my apocalypse kit, but I haven't looked into how long they're really good for... easily thrice their expiration date which is already many years. Vitamin deficiencies can become big problems with limited food varieties. Multivitamins aren't ideal, but they can suffice.
Powdered milk lasts quite a while. Yeast does too, but not flour so much.
Lab-grade ethanol is cheap (~$10/gal. for 90%), lasts forever, makes a good sanitizer, and it'll getcha obliterated in a pinch if you're so inclined.

As long as you keep it dry, sugar doesn't go bad. Lots of calories and you can mix it up with yeast, water and the syrup from those 20-year-old canned peaches to create some prison hooch. You'll need a little nip to keep the edge off when you're fighting zombies and assorted crazies.

Honey in large quantities sealed away from moisture may last forever, but smaller quantities in a humid environment will start to grow stuff eventually.

I've had a half-bottle of molasses in the refrigerator for years. No one will eat that nasty stuff.

But I had a jar of honey that was pushed back behind other things ..and it went dry and crystallized. You can't say it lasts forever.

Salt (iodized and non iodized). Salt tends to get overlook as necessary nutrients go. Plus, iodized or not, it's a good for wound care and as a mouth rinse. It can also be employed in long-term food preservation and various cleaning wounds. As well as, preventing goiters when it is iodized.

Lard keeps for a long time and can be used in any application requiring fat or grease. Aside from cooking/edible uses you can make soap, use it for skin protection and for any mechanical polishing or lubrication purposes. This really applies to any natural fat, but if we're picking pre-packaged then, lard it is.

Grain alcohol or ethanol, which was already mentioned. Sanitizing, and fuel (for fire starting or engines.)
Failing that, I think they're making Twinkies again and there's always Spam.

Powdered Peanut Butter. Comes in 2 flavors, regular and chocolate. Just add water to the powdered portion you want to eat. Lasts indefinitely.
My dad was a Master Beekeeper and this is what he did with honey. Honey will crystallize but you can easily re-liquify it by placing the glass jar on a cookie sheet and put it in the oven at the lowest temperature an oven will go - somewhere between 150 and 200 degrees until liquid again (3-4 hrs). Or liquify it in the jar in a pan of hot water. It will take a while because you need to keep reheating the water. Don't boil the honey.