SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76d730b571f9acdecbdf0f4abb12218e136d0cea51a361a76b70ed8609268576' 
  AND token = '6hnBHft8uSwc/5030Jym06gYFa6wDD0psBqMebCpfso=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

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