SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb15617c66653e51460f9b8d5998129f4db20fc177be9a1dc01b6bc394ced904' 
  AND token = 'EZQFi644RPIlL/dTD8/xYoR38/CFSgzlCNfwCOiKbhg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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