SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e453e5748076394d2e777489f7c0d76c854cddc057043e2687cebdbeb2dd2e3c' 
  AND token = '/WvesMx3OGyM/ZBeQw0Gh1hxvsc+xQoXMn1q3jf520w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE Impossible WHERE noticed after reading const tables