SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '18d6cecd3b46ad50f5d05cf53ac8cab1bf25e4a2d54c07ee1852fa94fe6bbf06' 
  AND token = 'TQoianOby/nvmhkriUwBlG+LEIn/z1vJgsGUVUcDg7k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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