mongoose query not working

I am trying to run a query in mongodb using mongoose like this :

mongooseModel.find().where(query).exec(function (err, data) {

});

And the value of the query is :

{ plate: 'BCF 5579', fuel_level: { $lte: 20 }}

In mongodb log, the query is going empty ({}).

If I replace the query with actual value like this:

mongooseModel.find().where({ plate: 'BCF 5579', fuel_level: { $lte: 20 }}).exec(function (err, data) {

});

It does work. What's wrong with the first option?

Here is the full code :

this.findAllByCondition = function (query, options, callback) {
            localLogger.debug('findAllByCondition');
            try {

                var sortBy = "_id";  // default sort order

                var pagingOptions = {
                    skip: 0,
                    limit: 30
                };

                if (options && options.limit) {
                    pagingOptions.limit = options.limit;
                }
                if (options && options.skip) {
                    pagingOptions.skip = options.skip;
                }

                if (options && options.sortBy) {
                    sortBy = options.sortBy;
                }

                if (options && options.sortOrder && options.sortOrder === "desc") {
                    sortBy = "-" + sortBy;
                }


                //{ plate: 'BCF 5579', fuel_level: { $lte: 20 }};

                //query1 = query;

                //query = req.query['q'];

                //var query1 = { plate: 'BCF 5579', fuel_level: { $lte: 20 }}


                var totalRecords = null;
                var results = null;
                async.parallel(
                    [
                        function (callback) {
                            mongooseModel.find(query).skip(pagingOptions.skip).limit(pagingOptions.limit).sort("field " + sortBy).exec(function (err, data) {
                                if (err) {
                                    callback(err);
                                }
                                else {
                                    results = data;
                                    callback();
                                }
                            });
                        },
                        function (callback) {
                            mongooseModel.count(query, function (err, count) {
                                if (err) {
                                    callback(err);
                                }
                                else {
                                    totalRecords = count;
                                    callback();
                                }
                            });
                        }
                    ],
                    function (err) {
                        callback(err, results, totalRecords);
                    }
                );
            } catch (exception) {
                localLogger.error('exception while trying to findOne ' + exception.message + " stack:" + exception.stack);
                callback(exception, null);
            }

        },