SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57287762437e2dc7202fb74b172e35d571b35817829fa55e65d786833899096c' 
  AND token = 'ejVhdLVx0XOxaMVgyR+jISvQIDpkUBnr0ARcVJ/AB7U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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