SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '374c1e89e7a3c743f618e918918249bc574ee718f912a8f469cd67cf900520c7' 
  AND token = 'enhqo0AmWlhZSHRWcFEvLnDp9HwhiIUAdVfZf5AXPUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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