SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7e2804e30e2b46277c0cf49d1955ffd6877a021a24d09ed8ddfe88a8871f844' 
  AND token = '2avl2aKeF0J4tlxsTo7pV74y1flmA+bD/PuamUHW4S8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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