SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9570cbca88484dc6ad02f54dc9a6de833d91b763d59fa4ee8342f3578ad66c5a' 
  AND token = 't+G2JgzYsA3B1KiMWsNM99IWo1hOyEDv14cybNeSRBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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