SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f475b898f3a1f15bf9172c3a7b2d758db30f5a38ad0af1d42b029117a06704df' 
  AND token = 'p6KA7pnUoAwZRzA/hTczUSDZuokZ0jfqXos34FDahBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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