SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0dd5df42fd39145c634d33d9de0c7767a0926fb646e05c77d4b9c6e12ca96813' 
  AND token = 'nU0RyBdZdDhTJqYxif8XLjWHK+phctP5BWuE+VbuW18=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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