SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28559d56f1e094ff52c56ecb2802767ac7810bc37285bd160a7367ad43027376' 
  AND token = '1wg39gztZLfQUQSRlmp705sz9kNmfWXnj+8ItrtVLOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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