How to use the @sap/xssec.createSecurityContext function in @sap/xssec

var client = req.db;
		var query = 'select "jobId".NEXTVAL as nJobId from "DUMMY"';
		var jname = req.body.jobname;
		var jobid;
		var timestamp;
		var accessToken;
		if (req.headers.authorization) {
			accessToken = req.headers.authorization.split(' ')[1];
		} else {
			logger.error('Authorization header not found');
			res.status(401).json({
				message: 'Authorization header not found'
			});
			return;
		}
		xssec.createSecurityContext(accessToken, xsuaaCredentials, function(error, securityContext) {
			if (error) {
				logger.error('Invalid access token');
				res.status(401).json({
					message: 'Invalid access token'
				});
				return;
			}

			if (securityContext.checkScope(SCOPE)) {

				client.exec(query, function(error, rows) {
					if (error) {
						logger.error('Error occured' + error);
					} else {
						jobid = rows[0].NJOBID;
						timestamp = new Date().toISOString();

return new Promise(function(resolve, reject) {
            if (!this._xsuaaService || !this._xsuaaService.credentials) {
                return reject(new Error('XSUAA (Source of token) service binding missing'));
            } else if (!this._credentials) {
                return reject(new Error('Leonardo IoT service binding missing'));
            }

            xssec.createSecurityContext(accessToken, this._xsuaaService.credentials, function (err, securityContext) {
                if (err) {
                    debug(`Token exchange error: ${err}`);
                    return reject(err);
                }

                debug('Security context created successfully');
                let grantType = xssec.constants.TYPE_USER_TOKEN;
                if (securityContext.getGrantType() === 'client_credentials') {
                    grantType = xssec.constants.TYPE_CLIENT_CREDENTIALS_TOKEN;
                }

                securityContext.requestToken(this._credentials, grantType, {}, function (err, newToken) {
                    if (err) {
                        debug(`Token exchange error: ${err}`);
                        return reject(err);
                    }