SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f23494fdffb768464e78944774728396afd94ea395e7a2e9e16c253acead801b' 
  AND token = '5cBmNucoi9FSzIx82BbUSKoyr5ITJRL0sri6wBRwtNA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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