SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '407950160df100cd1600662f4f69a28b5fb1b55968e04a2396f5f3d333afb575' 
  AND token = 'AKbfjBUdRqd1CyKiBH563ntZCZeSZRlgYq5nxWzIun0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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