SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '96291591b9286e16eaf706040334afd673e12e297b15ee9971a82c6319a606b4' 
  AND token = 'GwrZ60YP/kYp22IeXBngE2+YNzBzSB+uYqMBqoIf7js=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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