SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8fec1bfe181e15715ee4717537d9f41ee6340a688615abefe0607430ca0da2e5' 
  AND token = 'kSa3fjHsBtwv3g2dhC8xIizdDDDegFyQD+gc3cUFnFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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