SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '204b2a15a3c41a35b8fd9bcbbd69972b3415e008fc7d20a216630d39101e4fe6' 
  AND token = 'zomkSlOAtAHlGnTcWU2Qx/ZvSy/9hz1CMoQKBGKFm0U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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