SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71c29bf98442db6817cb1ec85aa02c61f4f2c88e9a1f966e48059a11d989ea9a' 
  AND token = 'UuCh113wDT3/CBvdHRKqiQzqhWvndDlsmJ7FgEpob9c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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