Yes, LOX is a Scrabble word!

Letter values in Scrabble US: L 1, O 1, X 8.

Is it a valid word?

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

a bluish translucent magnetic liquid obtained by compressing gaseous oxygen and then cooling it below its boiling point; used as an oxidizer in rocket propellants
brine-cured salmon that is lightly smoked

Also: liquid oxygen.