SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'febb239b52f94b291ecdb2ea630cbcb601f6451624fcfeed51ab3c63fe94f7cf' 
  AND token = 'uguYFCbCSN1ebXj8Z/shln5L8+Hl+qLql3UYjlOGtWs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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