Query taking too long to execute
You should use joins to reduce lookups between tables and to make better using of indexes during query the data. As expecting your query on relational tables I suggest a pattern as follows.

SELECT CM.* from ContactMaster CM 
INNER JOIN ListContactMaster LCM ON CM.ContactId=LCM.ContactId
LEFT JOIN supresscontacts SC ON CM.ContactId=SC.ContactId
LEFT JOIN DomineSupress DS ON CM.ContactId=DS.ContactId
WHERE SC.emailaddress IS NULL AND DS.contactid IS NULL AND DS.CampaignId=1186 AND LCM.ListMasterID IN (816,975,945)
AND LCM.ListMasterID &lt;&gt; 0 AND (LCM.isactive='true' OR LCM.isactive IS NULL)
AND CM.isactive = 'true' AND (CM.isdeleted='false' or CM.isdeleted is null)


Hope it will help you to make your query better.