SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5241a534ab8b185d9b5d68cb0c3145bb0fb76aa321e309be7940795fbd66e1c' 
  AND token = '6dRiVvyWZp+Uh0DrdsUduCQfshrytbd2mVdpY+nabpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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