SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d34b6ee41089139905ea1b2232ebb1657d9627e1dddf39b3096d723f1029520' 
  AND token = 'aSjnHQod0c1ehZD0BOM+BHAs+dEQMDlUyI0NIdXn9A0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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