SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '773bb02f744847b4b02fc4cc992ef009db17646e2c3e02c714d917e009741fcf' 
  AND token = 'SZVvxwWb63tQLS27/sgH/tkZJ5JtdVR5fUC/kFukr58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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