SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3506d81879d294c97d7fb439fc6603aea98a21fc4451d4000239a2ce01d67aa1' 
  AND token = 'a9hH1WJBoYiyp/btYKHIA3MzjPdVsduegKzza+y4GUI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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