SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4eaa8c1a4a955b60437557d29ce22319db04fd7fa56d8b8cb71d427daf7cdc8' 
  AND token = 'DfGujLquBuEYDpHx6Ynl6ZNhGGXOiP2TSJxhXRTCcmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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