SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef2ca25a85492f01f5eca79bdfeb5245532c70918d79e149942f553cde687624' 
  AND token = 'LVRcBYnQf3fjbXETt+F3a89KZUKXfcnTFSYUAXghgrI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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