MySQL 8.0

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

CREATE TABLE messages
    (`id` int, `date` varchar(19), `uid` int, `sid` int)
INSERT INTO messages
    (`id`, `date`, `uid`, `sid`)
VALUES
    (454, '2018-11-18 10:12:16', 206, 10),
    (456, '2018-11-18 10:53:37', 206, 20),
    (467, '2018-11-18 13:00:02', 206, 10),
    (469, '2018-11-18 14:50:33', 206, 10),
    (452, '2018-11-18 07:11:56', 208, 10),
    (470, '2018-11-18 15:01:38', 208, 20),
    (455, '2018-11-18 10:51:29', 209, 10),
    (458, '2018-11-18 11:30:45', 209, 20),
    (459, '2018-11-18 11:35:08', 209, 20),
    (460, '2018-11-18 11:48:24', 209, 20),
    (462, '2018-11-18 11:55:12', 209, 20),
    (464, '2018-11-18 12:09:20', 209, 10),
    (465, '2018-11-18 12:30:15', 209, 10),
    (468, '2018-11-18 14:00:58', 209, 10),
    (471, '2018-11-18 17:25:19', 209, 20),
    (472, '2018-11-19 18:52:24', 209, 10),
    (453, '2018-11-18 08:38:23', 212, 10),
    (457, '2018-11-18 11:29:03', 212, 20),
    (461, '2018-11-18 11:49:54', 212, 20),
    (463, '2018-11-18 12:08:49', 212, 10),
    (466, '2018-11-18 12:52:11', 212, 10)
SELECT MIN(m1.id) AS m1_id
     , MIN(m1.uid) AS uid
     , MIN(m1.sid) AS sid
     , MIN(m1.date) AS m1_date
     , MIN(m2.id) AS m2_id
     , MIN(m2.sid) AS m2_sid
     , m2.date AS m2_date
FROM messages m1
LEFT JOIN messages m2 ON m2.uid = m1.uid AND m2.sid != m1.sid AND m2.sid = 10 AND
    m2.date = (SELECT MIN(date)
               FROM messages m3 
               WHERE m3.uid = m2.uid AND m3.sid = 10 AND m3.date > m1.date)
WHERE m2.id IS NOT NULL
GROUP BY m2.date


m1_id
uid
sid
m1_date
m2_id
m2_sid
m2_date


456
206
20
2018-11-18 10:53:37
467
10
2018-11-18 13:00:02

458
209
20
2018-11-18 11:30:45
464
10
2018-11-18 12:09:20

471
209
20
2018-11-18 17:25:19
472
10
2018-11-19 18:52:24

457
212
20
2018-11-18 11:29:03
463
10
2018-11-18 12:08:49

m1_id	uid	sid	m1_date	m2_id	m2_sid	m2_date
456	206	20	2018-11-18 10:53:37	467	10	2018-11-18 13:00:02
458	209	20	2018-11-18 11:30:45	464	10	2018-11-18 12:09:20
471	209	20	2018-11-18 17:25:19	472	10	2018-11-19 18:52:24
457	212	20	2018-11-18 11:29:03	463	10	2018-11-18 12:08:49