SELECT
SUM(CASE WHEN `last_sign_in_at` <= DATE_SUB(NOW(), INTERVAL 3 DAY) THEN 1 ELSE 0 END) AS '> 3 days',
SUM(CASE WHEN `last_sign_in_at` <= DATE_SUB(NOW(), INTERVAL 90 MINUTE) AND `last_sign_in_at` >= DATE_SUB(NOW(), INTERVAL 3 DAY) THEN 1 ELSE 0 END) AS '> 90 min',
SUM(CASE WHEN `last_sign_in_at` <= DATE_SUB(NOW(), INTERVAL 30 MINUTE) AND `last_sign_in_at` >= DATE_SUB(NOW(), INTERVAL 90 MINUTE) THEN 1 ELSE 0 END) AS '> 30 min'
FROM `table`
