SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4d3128c95aba5608889a213bba269c41a4b426aaa69567dc73a11e69f3d2ec43' 
  AND token = 'UIhQtAGisClNgkoTZTApmaHVMET67UqC8UY1KHXhhTk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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