xdmp.documentLocks("example.xml");
=>
<?xml version="1.0" encoding="ASCII"?>
<lock:lock xmlns:lock="http://marklogic.com/xdmp/lock">
  <lock:lock-type>write</lock:lock-type>
  <lock:lock-scope>exclusive</lock:lock-scope>
  <lock:active-locks>
    <lock:active-lock>
      <lock:depth>0</lock:depth>
      <lock:owner>
        <DAV:href xmlns:DAV="DAV:">http://example.com/~user</DAV:href>
      </lock:owner>
      <lock:timeout>120</lock:timeout>
      <lock:lock-token>http://marklogic.com/xdmp/locks/1c267a036b8480c3
      </lock:lock-token>
      <lock:timestamp>1290136652</lock:timestamp>
      <sec:user-id xmlns:sec="http://marklogic.com/xdmp/security">
        893641342095093063</sec:user-id>
    </lock:active-lock>
  </lock:active-locks>
</lock:lock>

//   The time is in epoch time, which is seconds from the start
//   of 1970, so this code does a little math on the values in
//   the lock document to figure out how many seconds are left
//   for the lock.  Assumes a lock on /example.json, for example
//   by running the following:
//
//  declareUpdate();
//  xdmp.lockAcquire("/example.json", "exclusive", "0", [], 120);

var lock = xdmp.documentLocks("/example.json").next().value.root;
var lockDuration = new Number;
lockDuration = lock.xpath(
  "/lock:lock/lock:active-locks/lock:active-lock/lock:timeout/fn:data(.)",
  {"lock": "http://marklogic.com/xdmp/lock"}).next().value;
var currentEpochTime =
     fn.round(fn.currentDateTime().toObject().getTime() / 1000) ; 
     // divide by 1000 to convert miliseconds to seconds
var startTime = new Number;
startTime = lock.xpath(
  "/lock:lock/lock:active-locks/lock:active-lock/lock:timestamp/fn:data(.)",
  {"lock": "http://marklogic.com/xdmp/lock"}).next().value;
var endTime = new Number;
endTime = startTime + lockDuration;
var secondsLeft = endTime - currentEpochTime;
var res = [currentEpochTime, endTime, secondsLeft];
res;

=>
1290136837
1290136832
115