The short answer is, “No.” Nowhere in Scripture is answered prayer used as assurance of our salvation.
There are times when for any number of reasons God sees fit not to answer our prayers. That does not mean He doesn’t love us, we are not one of His, or that we are not walking closely with Him. Sometimes too, the answer to our prayers comes weeks, months, or even years later.
Throughout Scripture our salvation is conditioned on one thing—trusting in Christ alone.
“Most assuredly, I say to you, he who believes in Me has everlasting life” (John 6:47).
If we have come to God as sinners, recognized Christ died for us and rose again, and placed our trust in Christ as our only way to eternal life, we are as certain of heaven as though we are already there.