SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fca523a01bf31a6d9da71c32ea2479bd9780bb7d18a59a2cf570a3b9d45ea58' 
  AND token = 'hu/DJRRKRjBhSjVzBOWXv0LeSgunSuBeFko8y4uvf28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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