SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '991d05be1634ec53d13fa715c8467df4b270108ace80e840c6dd24323fa69020' 
  AND token = 'NhcJVcv/Opw+0p92cNEv+NtbypRRe07rSkcnftKuRAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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