SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '438861f4a69a383af018a7c631917bc9779d7d4f480233984b6d165a7dc00f50' 
  AND token = 'sEhH8JqNqOyUxwW2I78WXMaEvUjgnT4SXyS1WMhsdRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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