SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6f1604ccf8f7cb74a6fff3f49cb6f3456a24db73f24b866b9f150f971eba721' 
  AND token = 'XqPwWmRVXgwRqG+Q6Z+uDmUuhS8Gn3Fj1qNevmokFMI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}