SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c3b9ab160bf3c3e6a45211838d07d914a4cd72b77b214403fab00a81ddc7e3d' 
  AND token = '3SDZfYb7j6Ch3l7+nD708T41Dfym7UoVKf/DaYUlHhk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

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