Yes, WORLDS is a Scrabble word!

Letter values in Scrabble US: W 4, O 1, R 1, L 1, D 2, S 1.

Is it a valid word?

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

everything that exists anywhere
people in general; especially a distinctive group of people with some shared interest
all of your experiences that determine how things appear to you
the 3rd planet from the sun; the planet we live on
people in general considered as a whole
a part of the earth that can be considered separately
the concerns of this life as distinguished from heaven and the afterlife
all of the living human inhabitants of the earth

Also: worldly concern, earthly concern, human race, human beings.