SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c31dcf148a10c7a10237a65317e8052b641b05d9d9093cd4d8472c3e20b31ed3' 
  AND token = 'VczV9V9Or5WzRJUlgnGfZQrHvroEAM+yEXrHXuZQ4Bg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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