Query resulting in MongoDB hang

gistfile1.txt

QUERY:

{ 
"$or" : [ { "searchCycle_secs" : { "$exists" : false}} , { "$where" : "(null == this.harvest) || (null == this.harvest.harvested) || (null == this.searchCycle_secs) || ((this.harvest.harvested.getTime() + 1000*this.searchCycle_secs) <= 1352397384946)"}] , 

"isApproved" : true , "harvestBadSource" : { "$ne" : true} , "extractType" : { "$in" : [ "Feed" , "feed"]}
}

FIELDS:

{ "_id" : 1 , "extractType" : 1 , "key" : 1 , "harvest.harvested" : 1 , "harvest.synced" : 1 , "searchCycle_secs" : 1 , "harvest.harvest_status" : 1}

ORDERBY:

{ "harvest.harvested" : 1}

LIMIT:

120