SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c180bdf9edf237f63d841285931a99fc540018e8eb6e5b04421cb5f8f48565b0' 
  AND token = 'SsxfGuLzOUvoXB2IM3O81+g2jVQeK/2NrBdy1zHK+II=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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