SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '45dbeb6c04ef0296808d58c7705053cebb12f07ec448ae47646047711ae60901' 
  AND token = '8NIigrOUtZTCj9eB8F+/PzbPEKg4ue9KPp3wkHR95hE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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