SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f68764a503338ee9a77bf350290bc2c989dfd9226510a18127babac8cc2ef48' 
  AND token = 'QpkoTv9hEeQvv5GHKOTSBzRcTcVtjx+pRkyVkuBjJU0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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