SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '820676a1ceacabb027ffa8a075b6dbb6011198bcc07c8c6f024cb4314e446e4f' 
  AND token = 'oGdaAlasDxA90YzUNmyzT3l6LtVKODLlLQpkNqVxxP8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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