SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '818d2bbefcb0efed71f8f894726394e0f94130b40a4203175c8ebe145cfee960' 
  AND token = '9aLJadysFTEK2RMe1EQb3hXmAoadMzYmAUrVbB43FVI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00050

JSON explain

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