SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af91d8aed7c08248bfb4ad7826fabd558105347eea9c2d4f53f093a2b6297323' 
  AND token = 'KXRz8tQXGovPDFDuEl1t7hhAUOSa0rKZcbZQSWtBer8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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