Aqui está a resposta para minha pergunta. Isso funciona.
DELIMITER $$
CREATE EVENT IF NOT EXISTS Extract_Users
ON SCHEDULE EVERY 1 Minute COMMENT 'Extract_Users'
DO
BEGIN
SET @sql_stmt := concat("SELECT userID, email, id FROM user_table.user_info INTO OUTFILE C:/path/path/desktop/test/Users-",DATE_FORMAT(now(),'%Y-%m-%d_%H%i%s'),".xls'");
PREPARE extrct FROM @sql_stmt;
EXECUTE extrct;
DEALLOCATE PREPARE extrct;
END $$
DELIMITER ;