I have a very slow running query, and I've isolated the problem down to the following SQL.

SELECT
  ...
FROM
    TableA a(nolock) 
    inner join TableB b with(nolock) on (b.Id = a.Id AND b.Date>= isnull(@timestamp_start, '17530101') AND b.Date < isnull(@timestamp_end, '99991231'))

• a = 2million+ rows

• b = 2million+ rows

• b.Id => Index, unique, non-clustered

• a.Id => Index, unique, non-clustered

• b.Date => Index, non-unique, non-clustered

This takes several minutes without returning a result even for a single day date range. On my local machine here's what the execution plans looks like:

Why would this query be slow and how can I fix it?