Yes, MAYA is a Scrabble word!

Letter values in Scrabble US: M 3, A 1, Y 4, A 1.

Is it a valid word?

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

a member of an American Indian people of Yucatan and Belize and Guatemala who had a culture (which reached its peak between AD 300 and 900) characterized by outstanding architecture and pottery and astronomy
a family of American Indian languages spoken by Maya

Also: mayan language.