SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9fb3d9e40421984d741732241f86062b8af6c2fe7e6b100ad4d360c23d510eb2' 
  AND token = 'zfHoYl2f9kqaiuBAVhm4DQ1wdSpuhbWNbmoAT4W/2BY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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