SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '800e882eb92f18ddc5368df42883f144fabd57f0efcd5e88fa346eb8a9d8dd4a' 
  AND token = 'VnD3sWdK6aiYxVFx1dg71//jkig2cAhmggJugsz2XdQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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