SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91f2343016b4c0860e4dc4e0c2cb8cbed746935aece967a415d48a88631d33ea' 
  AND token = '2W/I1CO5pwWZOLSpCkWWPj7s+oalsF8R/yAb/rTCj5w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00008

JSON explain

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