SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3601fef31d85d810e7b7928427a31b4b4bb72a0379c8823c6a06f38c80eb998' 
  AND token = 'cPxlTMvuJhqRxItaZEQIDWoTCOMAN1aAiVlQ5BmRG/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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