SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc447eca2dd769f698c42c0965ec5353b12b045dec74235ab4683272e8cd6349' 
  AND token = 'sXYcuH2+QczBypNruVTefcRgtAQ0YzlzD2OEIL03MAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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