SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dddff3dceda44f4570711a336914e375765b74c235b270f9bc33181f78aac879' 
  AND token = 'IEsIigNYgNYxbGRh1+1ZAdI4vHFRfH3duDxU5oaTntU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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