SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3143210cfcd076dc4c25a0431145dbaad3cdd237111c937979a4252db755f95a' 
  AND token = 'prGMCLNs5ymhxGTY8X+zyanRd8ECri8mLWzkuT7d28U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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