SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '715e68b5f440c69fa24f9be517e9cd1b1863b587232f6467b9a5f346698a7856' 
  AND token = '41TXLNK+w7HLdvsR8/U/SmGmcgMKFr3DPFbdF3lVweU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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