A never-reprinted short story that could've been produced as an episode of the original Twilight Zone...
...from Charlton's Space War #22 (1963).
Was this a longer tale edited down to only three pages?
It certainly feels like it, since there are many unanswered questions like...If these people are Tibetan, why are they dressed like the Flintstones...and why do they speak English?
How would they know anything about the Earth-Uranus War?
And why is it we have no idea how only Heffner survived?
Pencils by Dick Giordano, inks by Vince Colletta.
The writer is unknown, but the Grand Comics Database postulates Joe Gill as the most likely candidate.