DATADIR="/var/lib/mysql"

find "$DATADIR" -mindepth 2 -maxdepth 2 -name '*.MYD' -exec stat -c '%Y %n' {} \; \
| awk -v base="$DATADIR/" '
  {
    ts=$1
    path=$2
    sub("^" base, "", path)     # quita /var/lib/mysql/
    db=path
    sub("/.*$", "", db)         # deja solo el primer componente (la base)
    if (ts > max[db]) max[db]=ts
  }
  END { for (db in max) print db, max[db] }
' \
| sort -k2,2n \
| while read -r db ts; do
    printf "%-40s %s\n" "$db" "$(date -d "@$ts" '+%Y-%m-%d %H:%M:%S')"
  done