A simple Query causing high CPU in SQL Server 2008
Based on your schema it looks like trans_seq can't be null so I would remove the isnull from the select as that would have a small amount of CPU overhead in just checking the value that is returned from the max function. 

SELECT max(trans_seq) +1  
FROM inv_inventory_journal  
WHERE organization_id = @P0  
AND wkstn_id = '600' 


Also if your query is always setting the wkstn_id to a constant 600. You could create a filtered index on that column. 

USE [LKY_Xcenter]
GO
CREATE NONCLUSTERED INDEX [&lt;Name of Missing Index, sysname,&gt;]
ON [dbo].[inv_inventory_journal] ([organization_id],[wkstn_id])
INCLUDE ([trans_seq])
WHERE [trans_seq] = 600;
GO


The nice thing about filtered indexes is that from an IO standpoint they only contain the rows that satisfies the where statement defined in the index so you could get better performance from them.

One thing of note with the filtered indexes is that in order for the query optimizer to use them the value in the where clause must be a constant in the query.  

Here is a couple of references to using filtered indexes:
MSDN

Brent Ozar