SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c236f33337afce44e3af50d059e736f88f37d5b4b6597c2d599700b5641175c' 
  AND token = 'STomwXg243fTQZ+q8zW4pIdv/X16SK95W+ZgPBD0wdc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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