SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '943b82233330c71cf3a11c1c054b48a9d9f7a3b640ae1c41e4c1edee354c9cb8' 
  AND token = 'q2lpdtSUGqNuBl8WOvXzhOlwJlVFtWQjz7bPnh2xsCU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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