SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99fc6c7e1bf1b928119fca85fe8ba3c885d08be6064905132609e39c3f3aacf6' 
  AND token = '389GexIIPNWHysdzpYFv0+GhH6th9xJuDp/pl1JhD+k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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