SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '8a8239a1016665296dc391383805f84932dea42d113806dc8a4720e5fb94724a' 
  AND token = 'NUh3HxZQywJSCRCGfMDTNGS8Rgkuhx6PeQRyBBOZ5iY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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