SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0dae58b8e2aca2433f58df67a644d6197cb191afda5ce5548c61a5de648b36f7' 
  AND token = 'cLj8/IXZeU//cZmXO1v3KkE7W6owVSYvj6znuO/FPRw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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