Index: sql/opt_explain.cc
===================================================================
--- sql/opt_explain.cc	(revision 1)
+++ sql/opt_explain.cc	(working copy)
@@ -1057,6 +1057,11 @@
             return true;
           fmt->entry()->col_attached_condition.set(c);
         }
+        else if (select->quick->unique_key_range())
+        {
+          if (push_extra(ET_none))
+            return true;
+        }
         else if (push_extra(ET_USING_WHERE))
           return true;
       }
@@ -1689,7 +1694,12 @@
 {
   join_type jt;
   if (select && select->quick)
-    jt= calc_join_type(select->quick->get_type());
+  {
+    if (select->quick->unique_key_range())
+      jt= JT_CONST;
+    else
+      jt= calc_join_type(select->quick->get_type());
+  }
   else if (key != MAX_KEY)
     jt= JT_INDEX_SCAN;
   else
Index: sql/opt_explain_traditional.cc
===================================================================
--- sql/opt_explain_traditional.cc	(revision 1)
+++ sql/opt_explain_traditional.cc	(working copy)
@@ -186,7 +186,11 @@
     qep_row::extra *e;
     while ((e= it++))
     {
-      DBUG_ASSERT(traditional_extra_tags[e->tag] != NULL);
+      /* when unique_key_range() is true, ET_none is set */
+      //DBUG_ASSERT(traditional_extra_tags[e->tag] != NULL);
+      if (e->tag == ET_none)
+        continue;
+
       if (buff.append(traditional_extra_tags[e->tag]))
         return true;
       if (e->data)