SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '250dc4998b0da656899d7e60781e2ccb0493b153fc9a4d4b933fba38c70ba307' 
  AND token = 'gJd948sHkFNGgWwwFnXGtP2KSkivXoWdLRM915fc6ME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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