SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c740bc6439a6d57b9e386528f27160faf29964eae2f8d37e3372aa97385937bf' 
  AND token = 'KwBkMASaimT1uyc6ZrLuZNiLWpJlMpXrCU+VjPsWQ64=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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