SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52d70bc7acd23c929d232e638186540f2c7b211c1becf5aa72cfcc01f33f0df5' 
  AND token = 'KseVno6cfDbUDtr5RhTD3vrPCsVKMR5oJ+Yw5roP4ac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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