SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9da3927034d50a5b98372c82bc3e45da204bf3802ebc43afc0d8635ee338490' 
  AND token = 'r4vWCmj7abXafv+J60ti8Ac9+ARiOg+HEjYol81jpwE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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