SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f93135a7caebff5780c56fcc062b2e0bd1c1ca523a74dc13dae48215273b03f' 
  AND token = '6J5mxM8VUN6f9aQrWIdWxSdGUi1nsbH4IjFhBryuBRs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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