SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '783e97b780c315dca29aadcbd45ae1f6c429948cd61a67fe208f5452eff9bb26' 
  AND token = 'k4PnnitS+ezSxCF7RQDm3JNenQBkUgpix5Mj3gwxz+U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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