SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82d448c0c0d4c4885edab154928a86f354a883d1a28b635ae140ebb3eabe3789' 
  AND token = '0a+iYbqpQWfAJw0IUHja4jqpyf48o8XVCPzKBgSB7Og=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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