Identify MySQL create version from data files
Open the .frm file with a hex editor. Go to offset 0x33 and read four bytes. Convert to decimal, keeping your endianness in mind.

Examples:


c0c30000 --> c3c0 --> 50112 --> version 5.1.12
64c50000 --> c564 --> 50532 --> version 5.5.32
b2860100 --> 186b2 --> 100018 --> version 10.0.18 (MariaDB)
19870100 --> 18719 --> 100121 --> version 10.1.21 (MariaDB)


Sources:


MySQL Internals Manual
a percona.com blog entry