select
 t.*
from
 MyTable t cross join
 (select top (1) id from MyTable order by id) a(id) cross join
 (select top (1) id from MyTable order by id desc) b(id)
where
 t.id = a.id or t.id = b.id;

select t.*
from MyTable t
join (select top (1) id from MyTable order by id) a(id) on t.id = a.id
join (select top (1) id from MyTable order by id desc) b(id) on t.id = b.id;

declare @tbl table (id int identity(1,1), value varchar(255))

insert into @tbl (value) values ('test1'), ('test2'), ('test3'), ('test4'), ('test5')

;with min_max (id_min, id_max) as (
    select
	  MIN(id),
	  MAX(id)
    from @tbl
)
select t.*
  from @tbl t
      join min_max m on t.id in (m.id_min, m.id_max)

--Вариант №1
WITH cte
AS (
	SELECT id,vv
	FROM [export_test].[dbo].[first_t_no_index]
	)
SELECT id,vv
FROM (
	SELECT TOP 1 *
	FROM cte
	ORDER BY id ASC 
	) s
UNION
SELECT id,vv
FROM (
	SELECT TOP 1 *
	FROM cte
	ORDER BY id DESC
) s

--Вариант №2
WITH cte
AS (
	SELECT *
		,row_number() OVER (PARTITION BY 1 ORDER BY id ASC) f
		,row_number() OVER (PARTITION BY 1 ORDER BY id DESC	) l
	FROM [export_test].[dbo].[first_t_no_index]
	)
SELECT id,vv
FROM cte WHERE f = 1
UNION 
SELECT id,vv
FROM cte WHERE l = 1