SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43328643ca20b4a51dc07da7a03360659bc273a62826484f168acd9d239de41a' 
  AND token = '5FWEr1phKUsucRmNmKAp4GDDT7TSj7cD8zlKkZYhsys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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