SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '88ac266388d3b35169b15dbc62123ca00b21068a20cdba19403c2c7df78a6e28' 
  AND token = 'GDjV3QR3vzLQBdkKKGssmrqQy7VMk4vG9R8rcWt42pA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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