SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a785ad2fa630fb4a4043eff3479a588b4912eef63cccd841bb1cf82cfc65531' 
  AND token = 'TK2Jn2GlepWsEFS8OUdihRy58jaF2eXmWBafekq5zls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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