SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '376212632ac16d12aca845b2af73d90341f78e4f50f8d501307181f130bfe816' 
  AND token = '4xACpjseF25xNn9m7OmC4sXugPvcEwpXX9fbuE1lGR8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}