SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7dd742d9810377938e9d220a23bb460231be7d1b9134cfc83bf6afc5e76e8569' 
  AND token = 'TxDHZ6ToURGRjZsz2hnduxA5gOdYQ5v69uI7zArFrPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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