SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4dd970e79c1f0f981f94644714448c5690dfeb4543c0c1b27c04f65efd8dca79' 
  AND token = '2bdp/hYL9v9havbJ2W8Qow+wPDncgIxj8RkuGzLv2cY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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