SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a68b969cec496f8817e3d1aa07b2490422e107e97985fe3165a80edff62ccb19' 
  AND token = 'QKLzEiP4a5GE3KXpXz999ukVKmb8nPladORO6zixqRk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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