create table users
(
  id int,
  email varchar(100),
  is_active tinyint(1),
  created_at int
);

insert into users values (1, 'user1@mail.ru', 1, unix_timestamp());
insert into users values (2, 'user1@mail.ru', 1, unix_timestamp() + 1234);
insert into users values (3, 'user1@mail.ru', 0, unix_timestamp() + 123456);
insert into users values (4, 'user2@mail.ru', 1, unix_timestamp());
insert into users values (5, 'user2@mail.ru', 1, unix_timestamp() + 1234);
insert into users values (6, 'user2@mail.ru', 0, unix_timestamp() + 123456);

select *
from
(
  select *
  from users
  order by is_active desc, created_at desc
) u
group by email // выбрались записи с id: 2 и 5 (как мне и надо было)

create view ordered_users as
select * from users order by is_active desc, created_at desc;

create view unique_users as
select * from ordered_users group by email;

select *
from unique_users // выбрались записи с id: 1 и 4 (неверно)