Zabbix and logrt.count doesn't get data
From Zabbix version 3.4+, Perl compatible regular expressions (PCRE) are implemented in the Zabbix frontend/backend. Your regexp doesn't look right:
$ touch req_log2018-06-26.txt
$ ls -lah | grep -P '^req_log.*.txt$'
<empty result>
$ ls -lah | grep -P 'req_log.*.txt'
-rw-r--r--. 1 root root 0 Jul 12 20:37 req_log2018-06-26.txt
Try:
logrt.count["/var/log/req_log.*.txt","TIMEOUT"]