SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42a7771b40e1f1a5bbcc2ca9338020482ec8103db5450fd1ffeee6e96b856cfb' 
  AND token = 'o836v1WsyuAHa4ctJYIiqgONFvLRCvzK/QBd1Utddu4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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