SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4f8b7f592599291154de1d9b24b60199edbfe3da2507fbdc463d8e56cf9a1c0' 
  AND token = 'KRzFTcqfpll6fosnIUR2yvlKY3fFEe3KNGcGqWTouDM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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