SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83a4b82afa73da46a3838e0d5786f27f4e9e23e2b628ff69cc57ef5fa609b7ae' 
  AND token = 'LTz2SfhdrdSZNwKPfXdFneov7+y6KvMVrtG1rEK5Qpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}