SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3799f8b9c69a0a4e8924a6f3075e4793e334ed824f57b6bb05da16935b854bd1' 
  AND token = 'g5aDXdzBJHAzWFIe1WkLgq9P/+RLBbhOkfsOsWFmDUc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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