Query on Javascript get error Malformed_Query

Question

I create list button OnClick Javascript Button on Lead. it will update the Is_Picked__c checkbox on selected record whenever i click the list button. but i still get MALFORMED_QUERY. Any thoughts?

{!REQUIRESCRIPT("/soap/ajax/35.0/connection.js")}
var records = {!GETRECORDIDS($ObjectType.Lead)}; 
var leadCheck = sforce.connection.query("SELECT Id, Is_Picked__c,Last_Seen_By__c FROM Lead WHERE Id ="+records[0]+" LIMIT 1");
var records1 = leadCheck.getArray("records");
var lead = records1[0];
var newRecords = [];
if (records[0] == null) { // if they dont pick any lead
alert("Please select at least one row") 
}
else if(records.length>1) { //if they pick more then 1 lead
alert("You only can pick one lead") ;
}
else if(lead.Is_Picked__c){
alert("This lead already picked by "+lead.Last_Seen_By__c);
}
else{
for (var n=0; n<records.length; n++) 
{ 
        var c = new sforce.SObject("Lead");
        c.id = records[n]; c.Is_Picked__c = 'true';
        newRecords.push(c); 
} 
result = sforce.connection.update(newRecords);
window.open('/'+records[0]);
}

Answer 1

update your query : sforce.connection.query("SELECT Id, Is_Picked__c,Last_Seen_By__c FROM Lead WHERE Id =\'"+records[0]+"\' LIMIT 1");