MySql faster to use separate query or subquery?

Question

The following query took 0.2630 sec to select 2477 rows from the total of 85862 rows in the table

(SELECT 1, `name` FROM `tab1` WHERE `reg` = 5 and `lang` = 9 and `queue` = 
   (select min(`queue`) from tab1 where `reg` = 5 and `lang` = 9)
limit 5)
UNION ALL
(SELECT 2, `name` FROM `tab1` WHERE `reg` = 1 and `lang` = 3 and `queue` =
   (select min(`queue`) from tab1 where `reg` = 1 and `lang` = 3)
limit 5)
UNION ALL
(SELECT 3, `name` FROM `tab1` WHERE `reg` = 3 and `lang` = 11 and `queue` =
   (select min(`queue`) from tab1 where `reg` = 3 and `lang` = 11)
limit 5)

Will there be, theoretically, any benefit to performance if, in order to detect MIN(value) of a column, I will run a separate query instead of sub-query?

columns reg and lang are indexed, queue is not

EXPLAIN:

| id | select_type | table       | type        | possible_keys | key      | key_len | ref  | rows| Extra
-----+-------------+-------------+-------------+---------------+----------+---------+------+-----+---------------------------------------
| 1  | PRIMARY     | tab1        | index_merge | reg,lang      | lang,reg | 1,1     | NULL | 813 | Using intersect(lang,reg); Using where
| 2  | SUBQUERY    | tab1        | index_merge | reg,lang      | lang,reg | 1,1     | NULL | 813 | Using intersect(lang,reg); Using where
| 3  | UNION       | tab1        | index_merge | reg,lang      | lang,reg | 1,1     | NULL | 830 | Using intersect(lang,reg); Using where
| 4  | SUBQUERY    | tab1        | index_merge | reg,lang      | lang,reg | 1,1     | NULL | 830 | Using intersect(lang,reg); Using where
| 5  | UNION       | tab1        | index_merge | reg,lang      | lang,reg | 1,1     | NULL | 834 | Using intersect(lang,reg); Using where
| 6  | SUBQUERY    | tab1        | index_merge | reg,lang      | lang,reg | 1,1     | NULL | 834 | Using intersect(lang,reg); Using where
|NULL| UNION RESULT| <union1,3,5>|  ALL        | NULL          | NULL     | NULL    | NULL | NULL| Using temporary

Answer 1

MySQL should be running the "min" subquery only once for each group. Putting the value in a separate variable shouldn't really affect performance.

If you want to optimize the performance of this query, then create an index on tab1(reg, lang, queue) . This index will allow direct lookups for values without going through the "index merge" step.