SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9b709573a47ca492792bf99773b17b6dfc189064bff11d6e9325ec44c0021ad' 
  AND token = 'av3b7Iz4JAZIjF71nd/trXlW2VzlgANIxpOB8NIPgjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}