SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f3bbb8d38c7420709f3f9b1d4b6fe052f68996a7b47140259f46ac39c1d6fc2' 
  AND token = 'd8266KNQ9sW51ReXvHNuwiNRrmxuxg4F8zqQ6B/PFZg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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