create table test (
id int primary key auto_increment,
created_at datetime
);
insert into test (created_at) values
('2021-01-01 00:00:00'),
('2021-01-01 00:01:02'),
('2021-02-01 00:00:00'),
('2021-02-01 00:01:02'),
('2021-01-02 00:00:00'),
('2021-01-02 00:01:02');
select * from test where created_at like '%-01 00:00:00';