SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'cb39b84bff3b5bc399dd9deb0ff698fe39f220314bba10c82153eac14ea0a9de' 
  AND token = 'S3fVleP8WnoezHQjh/w+cZdRCqQnlz/YSgzFVNXyfYg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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