SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28f3851a479f71680483f1b09dd7ee294e57193908060c36f843269a05d12aca' 
  AND token = 'rVVRVL/rpU9RvBjeGAZmCd8JQuK68RGAPA38bMzZgJc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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