SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ecf81316b43f593cf731cec0b9a012299c9887b4633d7edd3885f045bd9b4c98' 
  AND token = 'dErNCaN2dqjERfwgxn4bVWaSbkXUnmbinQRH75wTu1s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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