SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '257c50ecb63e9338900833a13b0cb5da4150014e041d2f421a1c259de5bc3215' 
  AND token = 'VmVkUlJHLG45D3u7O3C6UcSG6Qkpdrh9FwA/kaUPrus=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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