SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c36b740444e4d11c142428f3a9bd3de6b3605b86687d91ae46a32b6c6a6349d0' 
  AND token = 'deLqnyEKJgRQmVJCi5FTqpSOf/pvMet+4OyWsyVLeAo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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