SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd852935243a52f6dc3cec5ae13b0fc928134101a56cd8b9bdda1e6728da9c38c' 
  AND token = 'TVH0DwA6WrbuWZV3ySuQaJeSlOXkWCsRscfrQ5Nzjl4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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