SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '392707fd0d551bb3e7ad8e7658f9b9c4c594172db1b2f16b68862bce95ce30c0' 
  AND token = 'BJj1gPuTge2OqhxrzO4/u3rXJxs8ChahjpAb14+gCdE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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