SQL with different behavior

Hi,

how can I analyze the behavior of this single query executed several times, which on some days has a significant elapsed time with almost 100% CPU time and a large number of buffer gets ?

RDBMS      : 19.0.0.0.0
CPU_Count  : 16
Num Cores  : 16
Block Size : 8192
OFE        : 19.1.0

SELECT  ...

FROM  zcptesl0

WHERE

  cptesleta = :etab

  AND cpteslpla = :plan

  AND cpteslref = rpad(:refer, 26, ' ')

  AND cpteslobl = rpad(:coobl, 10, ' ')

  AND key_mbr = 'ZCPTESL0'

  AND cpteslage = :agence

  AND cptesldev = :devise

ORDER BY

  cptesleta, cpteslpla, cpteslobl, cptesldev, cpteslage, cpteslcom

Best regards