SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f6d9b39534bf013fa6bce20d6cc22f5a43eb3e61b854d504f0b91f9946ee1eb' 
  AND token = 'PgIJJjzuXyN6JZ4+yUx804DTWRTcp7TFF2aMxl4lWjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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