SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd27963b999cb9c76985b523f259e7efa1112fddd9a442a64917e5fddccf63dee' 
  AND token = 'eT6QwAKyibUOzklnAG+2F6E0TVGhOuRusHBbwTQEOGg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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