I transferred the domain to Route 53 and created a DNS zone, but unable to verify using txt record.

Start by doing a lookup of the name servers for your domaint. On Linux/Mac you can use the follwoing command:

dig <myDomain.tld> -t NS

If the domain has been fully transferred and updated to Route 53 you should see 4 entries like the following (not exactly these 4) in the answer section.

;; ANSWER SECTION:
<myDomain.tld>	62605	IN	NS	ns-878.awsdns-45.net.
<myDomain.tld>	62605	IN	NS	ns-421.awsdns-52.com.
<myDomain.tld>	62605	IN	NS	ns-1911.awsdns-46.co.uk.
<myDomain.tld>	62605	IN	NS	ns-1165.awsdns-17.org.

If you do not see the awsdns entries, then the name servers for your domain are not correct or are still in the cache publicly due to TTL not expiring. In the answer section, the number just after the <myDomain.tld> is the TTL (time to live) which is how long then entry will remain in a cache before lookup again.

Please check this and update and we can dig deeper.

I tried the NS lookup, but it doesn't show anything. In route 53. I created a hosted zone, and there are 4 NS records and an SOA record.

In the Route 53 console, on the left under Domains heading choose "Registered Domains". On the right, choose your domain. Now in the main page under Details at the right you should see the Name servers for your domain. Choose Action > Edit Name servers and set these to the 4 name servers listed in your Public Hosted Zone.

Hope this helps!

Perfect, thank you very much for that information. This issue has been resolved.