validateTokenKey = function validateTokenKey(token, key) {
  if (!token[key]) {
    throw AWS.util.error(
      new Error('Key "' + key + '" not present in SSO Token'),
      { code: 'SSOTokenProviderFailure' }
    );
  }
}
Throws error is key is not present in token object.

@param token [Object] Object to be validated.
@param key [String] The key to be validated on the object.