SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16a647bb6fde99e0c0950292d51f11ddb41653e7f6e9148a5088600d1454a71f' 
  AND token = '2IkvCXAhDWUz1To0++hWAd59psKwSqhHbOI1BpPkhY0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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