SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4ebb102d7459f4fec0de653547d93622c5ec20b612ac7ed3051a8fd18baca795' 
  AND token = 'X7XYqoBELIvYYIcOD0Ug4GVCyIhg0eBT5i4VUVn8S3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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