SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '345a84ee41cc84f6103825298a7753b985b5535c3ff0ae685d36fa687b592dfe' 
  AND token = 'UMRdhYB5BoIGmJjn2d+cMuv0DOxwqnaYxLZT+IBV3nE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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