SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '50733fdf7d59e905f3f8b9ce69157fcbf8347ef0e09857849049aafad4fdac28' 
  AND token = '8kseZCUsykQ/shT1IWQZ48EzkBslMWiQoOnsciyj/w4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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