MySQL 5.5

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CREATE TABLE people (
  id int,
  person_id int, 
  meeting_time int
);

insert into people values
(1,	21,	123456),
(2,	21,	123457),
(3,	21,	123456),
(4,	22,	123470),
(5,	21,	0),
(6,	21,	123470);

Records: 6  Duplicates: 0  Warnings: 0


select *
from people;


id
person_id
meeting_time


1
21
123456

2
21
123457

3
21
123456

4
22
123470

5
21
0

6
21
123470


select c.*
from ( 
  select p.*
  from people p
  inner join (
    SELECT person_id, max(id) as id
    FROM people
    where meeting_time between 123451 and 123460
    group by person_id
  ) as s on s.id = p.id
) as c
inner join (
  SELECT person_id, MAX(meeting_time) as max_meeting_time
  FROM people
  group by person_id
) as s on s.person_id = c.person_id and s.max_meeting_time between 123451 and 123460


id
person_id
meeting_time