SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3486ced341fdc636ffc95f08c1d88c77a9f22cad93fae7886a305f515a122ee0' 
  AND token = 'LhjBmfWE4IuzmNw+HmS5IBkkC2HyB5qfcm/YmUOjKRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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