SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'eb3c2938e935999cdd155379ea6c79dc1fd0ae6ec6032e231dce3673850f5619' 
  AND token = 'mPaErO/kBFpUF/FVN6t3ybsH28MIB+sSLgwnJNliovw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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