There's a few Singapore offers available on lowendbox, but none of them advertise any anti-DDoS protection or unlimited bandwidth.
https://lowendbox.com/tag/singapore/
Most datacenters have anti-DDoS protection installed these days, but possibly there won't be support if it happens.
As far as I know with unmanaged servers and no extra anti-DDoS support, the IP will be nulled for 15 minutes during an attack, which renders the service inaccessible as to save everyone else in the building.
If anti-DDoS is absolutely needed, then consider paying extra for OVH:
https://www.ovhcloud.com/en-sg/vps/
There also seems to be some struggles getting unlimited bandwidth in Asia, however if you hit the bandwidth limit then simply offload the sv_downloadurl to a different cheap storage VPS elsewhere in the world.