I searched entire MySQL doc for info about how to check if row (InnoDB) is
locked for write but
i didnt found anything.
Supose we have 2 transactions
1st transaction do
SELECT some_field FROM table_a FOR UPDATE;
2nd transaction wants do check if row is in lock for write before
it isues SELECT some_field FROM table_a FOR UPDATE;
How to check ?
SELECT .. FOR UPDATE - causes client app to hang, server waits as long as
first transaction issue commit command...

Artur