SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4d252ca43b36dc43dae41fa7327a04e14adfef48cf8409975312b79c2b7f477' 
  AND token = 'UHhzU4ljQOVgCHV8/z9phFQ2e+KX2zU+lF8ydLSUQvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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