SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4fd8ec44b3774898335a65555a8d83a216a3b13d0abde7fc05f4c1ff76b3f6c' 
  AND token = 'KrYKlRPc6Kzpt7cPtyO4MqGRuve9R4wLspZhFr3WxpU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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