SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '855a2ba88840cfb539d270a5f8d9b8639d02effb41853b5a66ab02978ea452a6' 
  AND token = 'BpTR1WXiil/lj8lemFAKFcaN7ZE+YBwrccoGqOXPYNw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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