SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '311f4c1d02b36a0583d920205004a4fe468999e586bee4d5f9a7db3549c66ac9' 
  AND token = 'nhHKBEH1Dn+fG3OCQA5Y6NpO1NhvCoTVV8EBsRmvRIM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

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