SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86c0ff49905f4b6cd51fe5c00d773d5d59cf46c7e42d371986b63f646c4fd421' 
  AND token = 'nYnssuLbBgKvdJD+LttRlBdnD44zlWYa7QdSzLXHUqw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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