SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4af1341745e97385405611c8a70be00204b431173c503adbff529b10ed715f06' 
  AND token = 'R2aXiZ24MtuxT9CVFBslPiLI6cOhDOh9vustjhKwDk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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