SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f0d8f2d7bfcc48110cce5007e33731d05d1ceb6e308e272337af7598205f084' 
  AND token = 'v3xRqyjYlKSGJQ+hQWYzP7/1V3QaxTGCYUAduvQFvN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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