SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '972ae3098482f3a08d88cb5e116f711875684e339df8dd77917d820a730933f2' 
  AND token = 'ShMg7rjAPqXaEck6EPyxQokyZtYSTOFdIK+fyV0VTY8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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