SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a73a35deb3e0d5b363705817aac01b16f38250fcd74bafdeac1ed6802e479f3' 
  AND token = 'M9Ggn8rtBmjEIIih1oOoqC1vczADsSaiDlsKOQ5d4Ck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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