SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '008a6057e0a59eb45c8372f8cd9908771dcbb05e3d57a4ccff4c4d8f80288dac' 
  AND token = 'UEmjNzXLThXkTEMFDnSOT6SsETFuUjKvRtdZXd5Ql0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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