SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1d66ae878a28338d93f8c45674a53e51b1c5b31a9f839d91b332be4175143e8f' 
  AND token = 'U+COQOzEK9yAM97SD5MwXeHVKvQAjaCCyFuWVwYk+/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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