SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd48a999249476ad27da46d16d31eb33c0684a30970b84f029fbee83e4bc7cb33' 
  AND token = '2QDV4TuYnXwyUQarlOaX9z+9Xhln1bQhuewBumuHANI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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