SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51dbe190c332b005303e6b1f9b89c3638a6c7159abceec4e371f7c5f9ef629f4' 
  AND token = 'kOeOpWsnk+Lo/OhJ1e/U8fTZFa2jjpzFUzjX6DfMBgI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

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