SELECT @lastWeekMondayTime AS started, @lastWeekFridayTime AS ended
FROM (
    SELECT @lastWeek := DATE_ADD(CURDATE(), INTERVAL -1 WEEK),
           @lastWeekMonday := DATE_ADD(@lastWeek, INTERVAL (-WEEKDAY(@lastWeek)) DAY),
           @lastWeekFriday := DATE_ADD(@lastWeekMonday, INTERVAL (+6) DAY),
           @lastWeekMondayTime := CONCAT(@lastWeekMonday, ' 00:00:00'),
           @lastWeekFridayTime := CONCAT(@lastWeekFriday, ' 23:59:59')
) t