unusual behavior for non existent data

Hi,

I have notice this most unusual behavior for sql execution :

(1) data "LMtwOWRGIPzEqLvB" does not exists :

SELECT count(*) q
FROM CRD_RICNEGINC_REL_PAG RNIRP
WHERE RNIRP.LOT_LOTTO_ID = 'LMtwOWRGIPzEqLvB'

(2) and "xLMtwOWRGIPzEqLvB" does not exists as well :

(3) finally, data "1s9Qur4znDm2vwrs" can be found :

and next runs, cache helps execution time , like "Elapsed: 00:00:00.13" or "Elapsed: 00:00:00.09" .

So, questions are :
- why an specific data (that does not exists) takes so much time to fetch ?
- notice that any other non-existent data does not shows that behavior (only that one from scenario(1) ) ;
- also, when data is found, elapsed time is always acceptable, better than