If having a physical key image stored elsewhere is a concern, then a keyless combo lock is probably the simpler alternative. You just remember your key code (hopefully) and don't need to carry anything besides your memory.
If you lose both, well, there's only so much you can reasonably protect against.
And yes, I suggested a "keyless" code lock in case you lose the key ;)
In an emergency condition, the simplest action (the one with the fewest steps, protocols or devices) you can take to recover completely is the best action. Losing your key and phone while being chased by muggers (for example) is just such an emergency. If you have enough faculties to remember your key code, you can still enter your home even if you're naked.
I like to think of services like KeyMe, which I do think is a fantastic idea, as an extra nicety during non-emergencies.
Being able to get into my house immediately even after losing both phone and keys is not a priority for me. If I'm being chased by a criminal near my own house after losing my keys and phone, I'll just shout until the neighbors come out.
If you add a Z-Wave controller like SmartThings, there are many options, including with keypads if you don't have your phone: http://www.amazon.com/s/ref=nb_sb_noss_1?field-keywords=z-wa...