SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '3a176759914a6ce25bf27ecea9f9818ff6c537d6eae9cd9ee35f387e2bc85e71' 
  AND token = 'xJqBC0XwhkwQgFE76J8GNXv96p4QHsqWqJP4/8Z361M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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