explain on view shows derived while explain on select shows simple select type

Question

I have a view v which involves a couple of sub-selects in its SELECT clause plus a couple of joins by id or indexed column.

The view query is like:

SELECT col1, col2, (SELECT ... FROM subt) AS col3 FROM t1 JOIN t2 ON [..]

The fact is that if I query that view by col1, which is pk of t1:

SELECT * FROM v WHERE col1='some value'

the EXPLAIN shows a bunch of DERIVED tables, but if I run the same query on the view SELECT statement:

SELECT col1, col2, (SELECT ... FROM subt) AS col3 FROM t1 JOIN t2 ON [..] WHERE col1='some value'

those same tables show up as SIMPLE.

How's that? I need to fix that view because it is not using some indices (although all joins are by pk or indexed columns), but I'm stuck on those DERIVED rows and I can't go further on my analysis.

UPDATE

For comparison, I've run a couple more explains on a view that doens't show these different execution plans for the same WHERE clause.

Given the view v1 create with CREATE VIEW v1 AS v_select_stmt, the plan for the query:

SELECT * FROM v_crm_v1 v WHERE v.id='some value'

gives all plan steps with select_type=simple.

The plan for:

[v_select_stmt] AND id='some value'

yields all the steps with select_type=simple too (and they're identical to the previuos query plan).

Finally, in the plan for:

SELECT * FROM ( [select_stmt] ) v WHERE id='some value'

the steps have all select_type=derived.