The best way to be sure it's the "real" plan is to see if the A(ctual)-rows, A(ctual)-time, buffers, columns etc. are populated in the plan. Without this information, it's tough to know if the plan is "good", even if you're seeing the actual plan used.
To get this information either you need to add the gather_plan_statistics hint or set statistics_level to ALL.
Doing this in SQL Developer and running in script mode I see:
alter session set statistics_level = all;
set autotrace on
select count(*) c from t;
C
----------
4
PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------------------------------
SQL_ID gkr95yuc0xv76, child number 0
-------------------------------------
select count(*) c from t
Plan hash value: 1750303431
------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers |
------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | 1 |00:00:00.01 | 4 |
| 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:00.01 | 4 |
| 2 | INDEX FAST FULL SCAN| SYS_C0033689 | 1 | 4 | 4 |00:00:00.01 | 4 |
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So yes, that's the "real" plan.