SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b296ba1b6a777499a8f3bfa79d29b53a705f0bc7705b9b14623581d64fcdaa9b' 
  AND token = 'WMpD05c7GIE0FrYccLEbYnrQI+6FzTePs9czyhQpqZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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