Yes, THRONES is a Scrabble word!

Letter values in Scrabble US: T 1, H 4, R 1, O 1, N 1, E 1, S 1.

Is it a valid word?

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

the chair of state for a monarch, bishop, etc.
a plumbing fixture for defecation and urination
the position and power of an exalted person (a sovereign or bishop) who is entitled to sit in a chair of state on ceremonial occasions