SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '5b4b9721c28fc6033157f1f2fd317655fe9e9839a2a936707869659134c69f8f' 
  AND token = 'XT6BJnTzjmhEaD/5QiIW33RTV/C2brCfnLmaiM8QL50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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