Yes, POKIES is a Scrabble word!

Letter values in Scrabble US: P 3, O 1, K 5, I 1, E 1, S 1.

Is it a valid word?

POKIES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a correctional institution used to detain persons who are in the lawful custody of the government (either accused persons awaiting trial or convicted persons serving a sentence)