SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91be039ac6a16b7c48e87c6e1a2854fec0d674e41a105117d3ff88d09c8d8d68' 
  AND token = 'x7UghADMXhwCE6BsFXXuwH4pEi9YTx4ZiEq3UHfv8gg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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