SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a5a6c6d48c4cedb4e57fcda9155d79fec54137c932389be6d1e48f1093fd919' 
  AND token = 'UQbOOZ9FfZT2SPaQEarB6KSlKdc6PQL/GAjVxKeUpzA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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