SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b90463783e93af421bb0392063466f8fbcc48281d51610b67d94309eaf542635' 
  AND token = 'OLCIahE5HdRL8EMPrApLyZt/T65r/2O3zfid5aeVwxc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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