I found several other statements online that this record isn't in FindMyPast but it was easy enough to find here: FindMyPast
In case the link doesn't work here's a transcription:
First name(s) William
Last name Lions
Baptism year 1621
Baptism date 23 Dec 1621
Parish Heston, St Leonard
Relationship Son
Father's first name(s) William
Mother's first name(s) Ann
County Middlesex
Record set Middlesex Baptisms
Category Birth, Marriage, Death & Parish Records