SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8d4f80ea8ed5248127ad01afe83400a9291cdc212ca5f13d2b6bbc1562177b5' 
  AND token = 'QvmgY5f3CnBbmfL3EmK7QTGOYlW8YFtZ36ysfu8sWys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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