Which Plan is the most efficient one?

Hello,

I have been trying to fine tune a query that involves this one table. The table contains 725,027 rows.

Plan 1
The original query completes in 6.2 seconds. The optimizer makes use of the clustered index. Performs a clustered index scan. The primary key is not used in the query.
Physical operation: Clustered Index Scan
Row Count: 725,027
I/O cost: 6.73
CPU cost: 0.39
Number of executes: 2
Cost: 3%
Estimated row count: 723,244


Plan 2
I created a covering index. Completes in 1.72 seconds. Uses the covering index but performs an index scan.
Physical operation: Index Scan
Row Count: 725,027
I/O cost: 3.09
CPU cost: 0.79
Number of executes: 1
Cost: 11%
Estimated row count: 723,244



Plan 3
I used 'set forceplan'. Completes in 2.31 seconds. Uses the covering index. Performs an Index Seek.
Physical operation: Index Seek
Row Count: 20,215
I/O cost: 0.00320
CPU cost: 0.000080
Number of executes: 10449
Cost: 22%
Estimated row count: 1


Plan 3 performs a seek, I/O and CPU is good BUT the number of executes is too high. Reads are high.

Would like to know which plan is ideal with regard to this table?


Thank you.