SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f2e9a03f348f2bfeb54cfeeda4e162e9957e39c795da3e11421dbda113729bf' 
  AND token = 'mjeK7nQA75/J003NcaSZ+Alcp9UrwscJ+BXaCG/5Ibw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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