SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '15b03e0d2d0a48b5a3b3c73b8e66c1f541d0f151ef11ab79e4730e977a69b7f9' 
  AND token = 'GKwazlh1FM6RqtaUgF9z573wYsg2Uj+nRBzao+8fIDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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