SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b815280db8d48545b0f64fcc641f36545d2a3e84f2ed79d077f421148a5468ed' 
  AND token = '2Tsk5MgL1WhY209m0UiBW5c0UhvA6/le3AZBtgA+Xr0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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