There is no such Expiry date for the EWS certificate. If the EWS certificate is issued in any month of the year, then it is valid till the 31st of March of the next year. So if you have a ews certificate, which is issued before the 31st of March 2022 then its expired and you have to reissue a new certificate for the fiscal year 2022-23. Now if you have a certificate which is issued after the 1st April 2022 then the certificate will be valid till the 31st March of 2023.

I hope this helps. Wish you a great day!