SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '78ab21bb024449aa20102cda7d8dafcb3cc754a27b94552ebed4212541e177f2' 
  AND token = 'AZRrFFopBdZHe49Nvtekd9IVuQZ5OfhQJWG7CEz6nEs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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