SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ac02296760b85f12b6615867d8800cf17094d7171016d30bfac56dcb2806be4' 
  AND token = 'xrYm0DRyaniqgU57/QSQkQbLjop6eB+NPsdDB/jxkRo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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