SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a76bb4997f3cb94f05b1d81058fb4ceeb2fbb9bf7805bd75acc97d516e47faf3' 
  AND token = 'UrlqkUXPt4jxiwXOEjxZEImfdsXhuQuhUmhxaBG2oPU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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