SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6908865ceb39adf6302e5b44712ecb2f445c7e6966f36c49f2f42e0f077b301' 
  AND token = 'wLYKVMjZY3AC8TXyKe3Hun9fheMD5uEYRCKs/pmmKaE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

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