MySQL 8.0

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CREATE TABLE t (
  id int NOT NULL PRIMARY KEY,
  device varchar(100),
  state int,
  timestamp datetime
);
INSERT INTO t VALUES
(250694, '1004-3-007294',  8, '2019-02-01 09:31:00'),
(250708, '1004-3-007294',  9, '2019-02-01 09:20:00'),
(250769, '1004-3-007294',  7, '2019-02-01 10:04:00'),
(250774, '1004-3-007294',  5, '2019-02-01 10:13:00'),
(250778, '1004-3-007294',  4, '2019-02-01 10:20:00'),
(250785, '1004-3-007294', 11, '2019-02-01 10:27:00'),
(250795, '3091-5-007208',  7, '2019-02-01 10:39:00'),
(250808, '1004-3-007294',  4, '2019-02-01 10:29:00'),
(250814, '1004-3-007294', 11, '2019-02-01 10:36:00'),
(250819, '3091-5-007208',  5, '2019-02-01 10:42:00'),
(250832, '3091-5-007208',  4, '2019-02-01 10:58:00'),
(250837, '3091-5-007208', 11, '2019-02-01 11:02:00'),
(250846, '3091-5-007208',  4, '2019-02-01 11:13:00');
SELECT t1.id, t2.id, TIMESTAMPDIFF(SECOND, t1.timestamp,t2.timestamp) AS diff
FROM       t AS t1
INNER JOIN t AS t2 ON t2.device = t1.device AND t2.state = 4 AND t2.timestamp > t1.timestamp
LEFT  JOIN t AS tx ON t1.device = tx.device AND tx.timestamp > t1.timestamp AND tx.timestamp < t2.timestamp
WHERE t1.state = 5 AND tx.id IS NULL


id
id
diff


250774
250778
420

250819
250832
960