SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3269d7016b1fb648395632a3b2129c4212754ae536746f18fff14e39516e7ec' 
  AND token = 'AYqc7mlsbtOfG1V5uYoVr89ouob2djFJ7KznUT2Y+XQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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