Fix bug in SSL ticket implementation removing keys of age < 1s

Fixes #1968.
diff --git a/library/ssl_ticket.c b/library/ssl_ticket.c
index 4d9116d..ad2d526 100644
--- a/library/ssl_ticket.c
+++ b/library/ssl_ticket.c
@@ -101,7 +101,7 @@
         uint32_t current_time = (uint32_t) mbedtls_time( NULL );
         uint32_t key_time = ctx->keys[ctx->active].generation_time;
 
-        if( current_time > key_time &&
+        if( current_time >= key_time &&
             current_time - key_time < ctx->ticket_lifetime )
         {
             return( 0 );