SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7534c67dec8cd40e1da977c668d67122110adeb55ace622cf55fb4d1f685f9c6' 
  AND token = 'gmJn3uiY4HtBAmK/V+gYXo2rCVFIRHn2rE0hej4EU9U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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