How to optimize select query in mysql

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MySQL

I have mysql table with 16000 records. I'm using mysql with asp.net. this is my query

CREATE   PROCEDURE `CustomerOrder_SelectItems_ByCompany`(
IN pCompanyId INT)
BEGIN


SELECT 
			 -1 as ItemId 
			,'Select Item' as Description3
            , 'Select No' as No
            , 'Select No2' as No2
			, 0 as RowNo

		UNION			
			SELECT S.ItemId
				, S.Description3
                , S.No
                , S.No2
				, 1 as RowNo  
            FROM itemmaster S 
            where statusId=1 AND S.CompanyId=pCompanyId 
END

this is dropdownbox select query. this take more times to load. I'm using select2 scripts to bind drop down data.