SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1da277dd40e2cd611a25999c103dd140e41b0280e0868ba343da4208ab7f4d86' 
  AND token = 'PDF5BTtLvShzWDrFomG6TGRyTZNZMk26FnaSucIavPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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