SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3902c2899a84b08b53e344c6a8cc42ffcdd578c84b8e8d67b226830258f07afe' 
  AND token = 'CzQTR/gKRohhy1K1rtyuOkLie9gUhjA0fuCG/qivcWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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