SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '43537e5f673f010ebf99faee7c906f70dfce1cc4c610bf3215cba6bf7dc84652' 
  AND token = 'dP1ZRvGECzxeZjhRifZD6ERjDEvusOTZPuC+GoomYv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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