Black Mystic Cats
Kirby Special #20.
I have this story in black and white (from a British reprint) as ell and the amount of detail is staggering. As I said earlier, these Tales of the Unexpected stories seem to me to be closer ot Kirby's Harvey work than to his work for Stan Lee soon after. Which fits, because they belong to his earliest DC work in 1957 (with some of his work for Havey even appearing after that, although we can't be sure he drew those in the order they were published).
From Tales of the Unexpected #17: