SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6d74c89e0381ef7db6caa23457955d91364af592a52c9b163fd3e9d8deea9166' 
  AND token = 'g7r3Hk4JMZfiZ2icZuHA0xItreU6/Ihs+kbmCqpOkII=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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